{"key": "lieber2016", "title": "Schedule matters: Understanding the relationship between schedule delays and costs on overruns", "authors": ["M. Lieber", "B. Donor"], "year": 2016, "venue": "2016 IEEE Aerospace Conference", "doi": "10.1109/aero.2016.7500722", "url": "https://doi.org/10.1109/aero.2016.7500722", "abstract": "This paper examines the relationship between schedule delays and cost overruns on complex projects. It is generally accepted by many project practitioners that cost overruns are directly related to schedule delays. But what does “directly related to” actually mean? Some reasons or root causes for schedule delays and associated cost overruns are obvious, if only in hindsight. For example, unrealistic estimates, supply chain difficulties, insufficient schedule margin, technical problems, scope changes, or the occurrence of risk events can negatively impact schedule performance. Other factors driving schedule delays and cost overruns may be less obvious and more difficult to quantify. Examples of these less obvious factors include project complexity, flawed estimating assumptions, over-optimism, political factors, “black swan” events, or even poor leadership and communication. Indeed, is it even possible the schedule itself could be a source of delay and subsequent cost overrun? Through literature review, surveys of project practitioners, and the authors' own experience on NASA programs and projects, the authors will categorize and examine the various factors affecting the relationshi", "grade": "A", "theme": "ch1_introduction", "source": "seed"}
{"key": "fine1999", "title": "A Proportional Hazards Model for the Subdistribution of a Competing Risk", "authors": ["J. P. Fine", "R. J. Gray"], "year": 1999, "venue": "Journal of the American Statistical Association", "doi": "10.1080/01621459.1999.10474144", "url": "https://doi.org/10.1080/01621459.1999.10474144", "abstract": "Abstract With explanatory covariates, the standard analysis for competing risks data involves modeling the cause-specific hazard functions via a proportional hazards assumption. Unfortunately, the cause-specific hazard function does not have a direct interpretation in terms of survival probabilities for the particular failure type. In recent years many clinicians have begun using the cumulative incidence function, the marginal failure probabilities for a particular cause, which is intuitively appealing and more easily explained to the nonstatistician. The cumulative incidence is especially relevant in cost-effectiveness analyses in which the survival probabilities are needed to determine treatment utility. Previously, authors have considered methods for combining estimates of the cause-specific hazard functions under the proportional hazards formulation. However, these methods do not allow the analyst to directly assess the effect of a covariate on the marginal probability function. In this article we propose a novel semiparametric proportional hazards model for the subdistribution. Using the partial likelihood principle and weighting techniques, we derive estimation and inference ", "grade": "A", "theme": "ch2_theoretical_framework", "source": "seed"}
{"key": "austin2016", "title": "Introduction to the Analysis of Survival Data in the Presence of Competing Risks", "authors": ["P. C. Austin", "D. S. Lee", "J. P. Fine"], "year": 2016, "venue": "Circulation", "doi": "10.1161/circulationaha.115.017719", "url": "https://doi.org/10.1161/circulationaha.115.017719", "abstract": "Competing risks occur frequently in the analysis of survival data. A competing risk is an event whose occurrence precludes the occurrence of the primary event of interest. In a study examining time to death attributable to cardiovascular causes, death attributable to noncardiovascular causes is a competing risk. When estimating the crude incidence of outcomes, analysts should use the cumulative incidence function, rather than the complement of the Kaplan-Meier survival function. The use of the Kaplan-Meier survival function results in estimates of incidence that are biased upward, regardless of whether the competing events are independent of one another. When fitting regression models in the presence of competing risks, researchers can choose from 2 different families of models: modeling the effect of covariates on the cause-specific hazard of the outcome or modeling the effect of covariates on the cumulative incidence function. The former allows one to estimate the effect of the covariates on the rate of occurrence of the outcome in those subjects who are currently event free. The latter allows one to estimate the effect of covariates on the absolute risk of the outcome over time.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "seed"}
{"key": "flyvbjerg2018", "title": "Five things you should know about cost overrun", "authors": ["B. Flyvbjerg"], "year": 2018, "venue": "Transportation Research Part A: Policy and Practice", "doi": "10.1016/j.tra.2018.07.013", "url": "https://doi.org/10.1016/j.tra.2018.07.013", "abstract": "This paper gives an overview of good and bad practice for understanding and curbing cost overrun in large capital investment projects, with a critique of Love and Ahiaga-Dagbui (2018) as point of departure. Good practice entails: (a) Consistent definition and measurement of overrun; in contrast to mixing inconsistent baselines, price levels, etc. (b) Data collection that includes all valid and reliable data; as opposed to including idiosyncratically sampled data, data with removed outliers, non-valid data from consultancies, etc. (c) Recognition that cost overrun is systemically fat-tailed; in contrast to understanding overrun in terms of error and randomness. (d) Acknowledgment that the root cause of cost overrun is behavioral bias; in contrast to explanations in terms of scope changes, complexity, etc. (e) De-biasing cost estimates with reference class forecasting or similar methods based in behavioral science; as opposed to conventional methods of estimation, with their century-long track record of inaccuracy and systemic bias. Bad practice is characterized by violating at least one of these five points. Love and Ahiaga-Dagbui violate all five. In so doing, they produce an exceptionally useful and comprehensive catalog of the many pitfalls that exist, and must be avoided, for properly understanding and curbing cost overrun.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "seed"}
{"key": "leunig2006", "title": "Time is Money: A Re-Assessment of the Passenger Social Savings from Victorian British Railways", "authors": ["T. Leunig"], "year": 2006, "venue": "Journal of Economic History", "doi": "10.1017/s0022050706000283", "url": "https://doi.org/10.1017/s0022050706000283", "abstract": null, "grade": "A", "theme": "ch2_theoretical_framework", "source": "seed"}
{"key": "callaway2021", "title": "Difference-in-Differences with multiple time periods", "authors": ["B. Callaway", "P. H. C. Sant'Anna"], "year": 2021, "venue": "Journal of Econometrics", "doi": "10.1016/j.jeconom.2020.12.001", "url": "https://doi.org/10.1016/j.jeconom.2020.12.001", "abstract": "Difference-in-Differences (DID) is one of the most important and popular designs for evaluating causal effects of policy changes. In its standard format, there are two time periods and two groups: in the first period no one is treated, and in the second period a \"treatment group\" becomes treated, whereas a \"control group\" remains untreated. However, many em- pirical applications of the DID design have more than two periods and variation in treatment timing. In this article, we consider identification and estimation of treatment effect parameters using DID with (i) multiple time periods, (ii) variation in treatment timing, and (iii) when the \"parallel trends assumption\" holds potentially only after conditioning on observed covariates. We propose a simple two-step estimation strategy, establish the asymptotic prop- erties of the proposed estimators, and prove the validity of a computationally convenient bootstrap procedure. Furthermore we propose a semiparametric data-driven testing procedure to assess the credibility of the DID design in our context. Finally, we analyze the effect of the minimum wage on teen employment from 2001-2007. By using our proposed methods we confront the challenges related to variation in the timing of the state-level minimum wage policy changes. Open-source software is available for implementing the proposed methods.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "seed"}
{"key": "social", "title": "Social Savings (Leunig 2010)", "authors": [], "year": null, "venue": null, "doi": "10.1111/j.1467-6419.2010.00636.x", "url": "https://doi.org/10.1111/j.1467-6419.2010.00636.x", "abstract": null, "grade": "A", "theme": "ch2_theoretical_framework", "source": "hall-of-shoulders:fogel"}
{"key": "difference", "title": "Difference-in-differences with variation in treatment timing", "authors": [], "year": null, "venue": null, "doi": "10.1016/j.jeconom.2021.03.014", "url": "https://doi.org/10.1016/j.jeconom.2021.03.014", "abstract": null, "grade": "A", "theme": "ch2_theoretical_framework", "source": "hall-of-shoulders:callaway_santanna"}
{"key": "whatb", "title": "What's trending in difference-in-differences? A synthesis of the recent econometrics literature", "authors": [], "year": null, "venue": null, "doi": "10.1016/j.jeconom.2023.03.008", "url": "https://doi.org/10.1016/j.jeconom.2023.03.008", "abstract": null, "grade": "A", "theme": "ch2_theoretical_framework", "source": "hall-of-shoulders:callaway_santanna"}
{"key": "differenceb", "title": "Difference-in-Differences with a Continuous Treatment", "authors": [], "year": null, "venue": null, "doi": "10.2139/ssrn.4716682", "url": "https://doi.org/10.2139/ssrn.4716682", "abstract": null, "grade": "B", "theme": "ch2_theoretical_framework", "source": "hall-of-shoulders:callaway_santanna"}
{"key": "bonneville2024", "title": "Why you should avoid using multiple Fine–Gray models: insights from (attempts at) simulating proportional subdistribution hazards data", "authors": ["E. Bonneville", "L. D. de Wreede", "H. Putter"], "year": 2024, "venue": "Journal of the Royal Statistical Society: Series A (Statistics in Society)", "doi": "10.1093/jrsssa/qnae056", "url": "https://doi.org/10.1093/jrsssa/qnae056", "abstract": "\n Studies considering competing risks will often aim to estimate the cumulative incidence functions conditional on an individual’s baseline characteristics. While the Fine–Gray subdistribution hazard model is tailor-made for analysing only one of the competing events, it may still be used in settings where multiple competing events are of scientific interest, where it is specified for each cause in turn. In this work, we provide an overview of data-generating mechanisms where proportional subdistribution hazards hold for at least one cause. We use these to motivate why the use of multiple Fine–Gray models should be avoided in favour of better alternatives such as cause-specific hazard models.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "semanticscholar"}
{"key": "lamidi2025", "title": "Cumulative Incidence Function in Competing Risks: A Case Study of Primary Biliary Cirrhosis in Liver Disease", "authors": ["Rasheed K. Lamidi", "Bello Ishola Sanni", "Saheed Kunle Ajibade", "B. I. Doroh", "Aishat Olaosebikan"], "year": 2025, "venue": "International Journal of Science for Global Sustainability", "doi": "10.57233/ijsgs.v11i4.991", "url": "https://doi.org/10.57233/ijsgs.v11i4.991", "abstract": "Competing risks have a potential to cause biased estimates in the context of survival analysis using both traditional tools like the Kaplan-Meier estimator and Cox proportional hazards model. This is especially applicable in Primary Biliary Cirrhosis (PBC) which is a chronic liver disease where the patients can die or undergo liver transplantation as a mutually exclusive outcome. This study used the cumulative incidence function (CIF) and Fine-Gray sub-distribution hazard model to measure competing risks in patients with PBC using data in the Mayo Clinic randomised trial of 312 patients. The likelihoods of death and liver transplantation as time progressed were estimated using CIFs which adequately considered competing events, and Fine-Gray was also used to determine the impact of D-penicillmain therapy versus placebo and the important prognostic factors. The findings revealed that, the cumulative death rates were always higher than the cumulative transplantation rates of the liver during the follow-up time. Even though the patients who were treated with D-penicillmain reported a slightly low mortality and slightly higher rate of transplantation compared to the patients provided with placebo; the difference was considered insignificant. Competing outcomes were found to be significantly predicted by age, ascites, disease stage, and platelet count and not by sex, bilirubin, and albumin. Altogether, the research proves that the competing risks approach is better in terms of its accuracy and clinical significance of assessment outcomes in PBC and the significance of CIF-based methodology in the assessment of treatment effects and prognosis in chronic liver disease.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "semanticscholar"}
{"key": "carydias2025", "title": "Engineering Visual Presentation E08: Tackling the 65% megaproject failure epidemic: six key levers amplified by digital and AI", "authors": ["P. Carydias"], "year": 2025, "venue": "Australian Energy Producers Journal", "doi": "10.1071/ep24445", "url": "https://doi.org/10.1071/ep24445", "abstract": "Engineering Visual Presentation E08 Capital megaprojects (>US$1 billion) face a 65% failure rate, defined as cost overruns ≥25%, schedule delays ≥5%, or significant operational problems. Our research reveals six critical factors driving failures. (1) People and organisation (25–26% of issues): 70% of projects understaffed; only 15% of organisations report high agility. (2) Technical challenges (21–23%): operators often unprepared, especially in complex environments. (3) Governance (18%): 58% of projects misaligned with strategy; short-term focus impacts lifecycle value. (4) External stakeholders (14%): early engagement failures lead to disruptions. (5) Contracting and procurement (12–13%): inefficient strategies impact schedules, costs, and quality. (6) Project management processes (6–9%): poor front-end loading (FEL) implementation; projects average 26 months late. Our work has identified key mitigations for each. (1) Secure experienced teams: hire proven leaders and their established teams; implement talent management programs. (2) Early technology screening: engage vendors early, opt for proven technologies with ‘frozen experience’. (3) Prioritise lifecycle value: use reference class forecasting for realistic predictions; integrate risk assessment into decision-making. (4) Proactive stakeholder engagement: identify and engage stakeholders early, tailor communication strategies. (5) Strategic procurement: leverage sourcing power, establish vendor relationships, pre-order critical items. (6) Thorough FEL: allocate sufficient budget and time for detailed scope definition and risk assessment; use rigorous peer reviews. We bring our case study where targeted interventions orchestrated through a digital asset in front-end engineering and design (FEED) mitigated >A$1.5 B in capital expenditure (CAPEX) costs for a megaproject. By addressing these six areas systematically, the industry can significantly improve megaproject success rates and achieve the coming energy transformation capital delivery wave. To access the Visual Presentation click on the link on the right. To read the full paper click here", "grade": "A", "theme": "ch2_theoretical_framework", "source": "semanticscholar"}
{"key": "carydias2025b", "title": "Tackling the 65% megaproject failure epidemic: six key levers amplified by digital and AI", "authors": ["P. Carydias", "R. Kennedy"], "year": 2025, "venue": "Australian Energy Producers Journal", "doi": "10.1071/ep24270", "url": "https://doi.org/10.1071/ep24270", "abstract": "Capital megaprojects (>US$1 billion) face a 65% failure rate, defined as cost overruns ≥25%, schedule delays ≥5%, or significant operational problems. Our research reveals six critical factors driving failures. (1) People and organisation (25–26% of issues): 70% of projects understaffed; only 15% of organisations report high agility. (2) Technical challenges (21–23%): operators often unprepared, especially in complex environments. (3) Governance (18%): 58% of projects misaligned with strategy; short-term focus impacts lifecycle value. (4) External stakeholders (14%): early engagement failures lead to disruptions. (5) Contracting and procurement (12–13%): inefficient strategies impact schedules, costs, and quality. (6) Project management processes (6–9%): poor front-end loading (FEL) implementation; projects average 26 months late. Our work has identified key mitigations for each. (1) Secure experienced teams: hire proven leaders and their established teams; implement talent management programs. (2) Early technology screening: engage vendors early, opt for proven technologies with ‘frozen experience’. (3) Prioritise lifecycle value: use reference class forecasting for realistic predictions; integrate risk assessment into decision-making. (4) Proactive stakeholder engagement: identify and engage stakeholders early, tailor communication strategies. (5) Strategic procurement: leverage sourcing power, establish vendor relationships, pre-order critical items. (6) Thorough FEL: allocate sufficient budget and time for detailed scope definition and risk assessment; use rigorous peer reviews. We bring our case study where targeted interventions orchestrated through a digital asset in front-end engineering and design (FEED) mitigated >A$1.5 B in capital expenditure (CAPEX) costs for a megaproject. By addressing these six areas systematically, the industry can significantly improve megaproject success rates and achieve the coming energy transformation capital delivery wave.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "semanticscholar"}
{"key": "berger2018", "title": "Subdistribution hazard models for competing risks in discrete time.", "authors": ["M. Berger", "M. Schmid", "T. Welchowski", "S. Schmitz-Valckenberg", "J. Beyersmann"], "year": 2018, "venue": "Biostatistics", "doi": "10.1093/biostatistics/kxy069", "url": "https://doi.org/10.1093/biostatistics/kxy069", "abstract": "A popular modeling approach for competing risks analysis in longitudinal studies is the proportional subdistribution hazards model by Fine and Gray (1999. A proportional hazards model for the subdistribution of a competing risk. Journal of the American Statistical Association94, 496-509). This model is widely used for the analysis of continuous event times in clinical and epidemiological studies. However, it does not apply when event times are measured on a discrete time scale, which is a likely scenario when events occur between pairs of consecutive points in time (e.g., between two follow-up visits of an epidemiological study) and when the exact lengths of the continuous time spans are not known. To adapt the Fine and Gray approach to this situation, we propose a technique for modeling subdistribution hazards in discrete time. Our method, which results in consistent and asymptotically normal estimators of the model parameters, is based on a weighted ML estimation scheme for binary regression. We illustrate the modeling approach by an analysis of nosocomial pneumonia in patients treated in hospitals.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "semanticscholar"}
{"key": "wolbers2014", "title": "Competing risks analyses: objectives and approaches", "authors": ["Marcel Wolbers", "Michael Koller", "Vianda S Stel", "Beat Schaer", "Kitty J. Jager", "Karen Leffondré", "Georg Heinze"], "year": 2014, "venue": "European Heart Journal", "doi": "10.1093/eurheartj/ehu131", "url": "https://openalex.org/W2030404218", "abstract": "Studies in cardiology often record the time to multiple disease events such as death, myocardial infarction, or hospitalization. Competing risks methods allow for the analysis of the time to the first observed event and the type of the first event. They are also relevant if the time to a specific event is of primary interest but competing events may preclude its occurrence or greatly alter the chances to observe it. We give a non-technical overview of competing risks concepts for descriptive and regression analyses. For descriptive statistics, the cumulative incidence function is the most important tool. For regression modelling, we introduce regression models for the cumulative incidence function and the cause-specific hazard function, respectively. We stress the importance of choosing statistical methods that are appropriate if competing risks are present. We also clarify the role of competing risks for the analysis of composite endpoints.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "openalex"}
{"key": "baerenbold2023", "title": "Reducing risks in megaprojects: The potential of reference class forecasting", "authors": ["Rebekka Baerenbold"], "year": 2023, "venue": "Project Leadership and Society", "doi": "10.1016/j.plas.2023.100103", "url": "https://openalex.org/W4388568299", "abstract": "Large infrastructure projects often suffer from cost and schedule overruns, mainly due to optimism bias and strategic misrepresentation. Reference class forecasting (RCF) offers a potential remedy. This study presents a comprehensive analysis of the RCF literature with the aim of providing practitioners with key insights and identifying areas for future research. Through a review of 41 selected papers, the paper shows that the effectiveness of RCF is mainly applicable to large-scale projects and depends on the definition of the reference class. The paper calls for the development of an empirically based framework for reference class formation and urges the exploration of RCF's adaptability across industries, challenging the current one-size-fits-all approach. Theoretically, the paper critically assesses the current applications of RCF, while practically it outlines directions for future research and improvements. Overall, the study emphasises the need for detailed, data-driven methodologies and highlights their potential for risk management in projects worldwide.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "openalex"}
{"key": "ray1988", "title": "A Class of $K$-Sample Tests for Comparing the Cumulative Incidence of a Competing Risk", "authors": ["Malcolm H. Ray"], "year": 1988, "venue": "The Annals of Statistics", "doi": "10.1214/aos/1176350951", "url": "https://openalex.org/W2073140442", "abstract": "In this paper, for right censored competing risks data, a class of tests developed for comparing the cumulative incidence of a particular type of failure among different groups. The tests are based on comparing weighted averages of the hazards of the subdistribution for the failure type of interest. Asymptotic results are derived by expressing the statistics in terms of counting processes and using martingale central limit theory. It is proposed that weight functions very similar to those for the $G^p$ tests from ordinary survival analysis be used. Simulation results indicate that the asymptotic distributions provide adequate approximations in moderate sized samples.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "openalex"}
{"key": "lau2009", "title": "Competing Risk Regression Models for Epidemiologic Data", "authors": ["Bonnie Lau", "Stephen R. Cole", "Stephen J. Gange"], "year": 2009, "venue": "American Journal of Epidemiology", "doi": "10.1093/aje/kwp107", "url": "https://openalex.org/W2154746519", "abstract": "Competing events can preclude the event of interest from occurring in epidemiologic data and can be analyzed by using extensions of survival analysis methods. In this paper, the authors outline 3 regression approaches for estimating 2 key quantities in competing risks analysis: the cause-specific relative hazard ((cs)RH) and the subdistribution relative hazard ((sd)RH). They compare and contrast the structure of the risk sets and the interpretation of parameters obtained with these methods. They also demonstrate the use of these methods with data from the Women's Interagency HIV Study established in 1993, treating time to initiation of highly active antiretroviral therapy or to clinical disease progression as competing events. In our example, women with an injection drug use history were less likely than those without a history of injection drug use to initiate therapy prior to progression to acquired immunodeficiency syndrome or death by both measures of association ((cs)RH = 0.67, 95% confidence interval: 0.57, 0.80 and (sd)RH = 0.60, 95% confidence interval: 0.50, 0.71). Moreover, the relative hazards for disease progression prior to treatment were elevated ((cs)RH = 1.71, 95% c", "grade": "A", "theme": "ch2_theoretical_framework", "source": "openalex"}
{"key": "zhou2025", "title": "In-hospital mortality from healthcare-associated infection by multidrug-resistant Pseudomonas aeruginosa: a competing risks analysis of a 4-year propensity-matched cohort study in southern China", "authors": ["Mouqing Zhou", "Evangelos I. Kritsotakis", "Baohua Xu", "Zhusheng Guo", "Yongfeng Zeng", "Bin Zhou", "R. Brinks", "Jiancong Wang"], "year": 2025, "venue": "GMS Hygiene and Infection Control", "doi": "10.3205/dgkh000597", "url": "https://doi.org/10.3205/dgkh000597", "abstract": "Background: Healthcare-associated infections (HAIs) caused by multidrug-resistant Pseudomonas aeruginosa (MDRPa) pose enormous challenges in healthcare. We examined the incidence and relative mortality rates of patients with MDRPa HAI compared to non-MDRPa HAI in southern China. Methods: A hospital-wide longitudinal cohort study was conducted using prospectively collected surveillance data from 2018 to 2021. Poisson regression was applied to estimate incidence rate ratios (IRRs). Propensity-score matching and competing risks regression analysis (Fine-Gray model) were employed to estimate subdistribution hazard ratios (sHRs) for in-hospital mortality comparing MDRPa to non-MDRPa infections. Results: Among 562 patients studied (mean age 58 years, 74% male, in-hospital mortality 13.7%), 278 (49%) had an MDRPa HAI and 284 (51%) a non-MDRPa HAI. The incidence rate of MDRPa HAIs increased over time (mean monthly IRR: 1.016, 95% CI: 1.007–1.024). No significant difference in 14-day in-hospital mortality between MDRPa and non-MDRPa HAIs were detected in the propensity-matched doubly-robust analysis (adjusted sHR: 1.07, 95% CI: 0.52–2.19). However, MDRPa HAI was associated with a lower probability of 14-day discharge alive (adjusted sHR: 0.44, 95% CI: 0.31–0.63), resulting in longer hospital stays. Conclusions: The study provided real-world evidence of the clinical burden of MDRPa HAIs in China, highlighting their rising incidence and direct effect on prolonging hospitalisation. The findings underscore the need for antimicrobial stewardship interventions to ensure timely de-escalation and optimised antibiotic therapy.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "semanticscholar"}
{"key": "diao2019", "title": "Quantifying time-varying cause-specific hazard and subdistribution hazard ratios with competing risks data", "authors": ["Guoqing Diao", "Joseph G Ibrahim"], "year": 2019, "venue": "Clinical Trials", "doi": "10.1177/1740774519852708", "url": "https://doi.org/10.1177/1740774519852708", "abstract": "<jats:p>Various non-proportional hazard models have been developed in the literature for competing risks data. The regression coefficients under these models, however, typically cannot be compared directly. We propose new methods to quantify the average of the time-varying cause-specific hazard ratios and subdistribution hazard ratios through two general classes of transformations and weight functions that are chosen to reflect the relative importance of the hazard ratios in different time periods. We further propose an [Formula: see text] -norm type of test statistic that incorporates the test statistics for all possible pairs of the transformation function and weight function under consideration. Extensive simulations are conducted under various settings of the hazards and demonstrate that the proposed test performs well under all settings. An application to a clinical trial in follicular lymphoma is examined in detail.</jats:p>", "grade": "A", "theme": "ch2_theoretical_framework", "source": "crossref"}
{"key": "ansar2014", "title": "Should We Build More Large Dams? The Actual Costs of Hydropower Megaproject Development", "authors": ["A. Ansar", "B. Flyvbjerg", "Alexander Budzier", "Daniel Lunn"], "year": 2014, "venue": "", "doi": "10.1016/j.enpol.2013.10.069", "url": "https://doi.org/10.1016/j.enpol.2013.10.069", "abstract": "A brisk building boom of hydropower mega-dams is underway from China to Brazil. Whether benefits of new dams will outweigh costs remains unresolved despite contentious debates. We investigate this question with the “outside view” or “reference class forecasting” based on literature on decision-making under uncertainty in psychology. We find overwhelming evidence that budgets are systematically biased below actual costs of large hydropower dams—excluding inflation, substantial debt servicing, environmental, and social costs. Using the largest and most reliable reference data of its kind and multilevel statistical techniques applied to large dams for the first time, we were successful in fitting parsimonious models to predict cost and schedule overruns. The outside view suggests that in most countries large hydropower dams will be too costly in absolute terms and take too long to build to deliver a positive risk-adjusted return unless suitable risk management measures outlined in this paper can be affordably provided. Policymakers, particularly in developing countries, are advised to prefer agile energy alternatives that can be built over shorter time horizons to energy megaprojects.", "grade": "B", "theme": "ch2_theoretical_framework", "source": "semanticscholar"}
{"key": "ahiagadagbui2014", "title": "Dealing with construction cost overruns using data mining", "authors": ["Dominic D. Ahiaga-Dagbui", "Simon Smith"], "year": 2014, "venue": "Construction Management and Economics", "doi": "10.1080/01446193.2014.933854", "url": "https://openalex.org/W1992699707", "abstract": "One of the main aims of any construction client is to procure a project within the limits of a predefined budget.&#13;\\nHowever, most construction projects routinely overrun their cost estimates. Existing theories on construction&#13;\\ncost overrun suggest a number of causes ranging from technical difficulties, optimism bias, managerial incompetence&#13;\\nand strategic misrepresentation. However, much of the budgetary decision-making process in the early&#13;\\nstages of a project is carried out in an environment of high uncertainty with little available information for accurate&#13;\\nestimation. Using non-parametric bootstrapping and ensemble modelling in artificial neural networks, final&#13;\\nproject cost-forecasting models were developed with 1600 completed projects. This helped to extract information&#13;\\nembedded in data on completed construction projects, in an attempt to address the problem of the dearth of&#13;\\ninformation in the early stages of a project. It was found that 92% of the 100 validation predictions were within&#13;\\n±10% of the actual final cost of the project while 77% were within ±5% of actual final cost. This indicates the&#13;\\nmodel’s ability to generali", "grade": "A", "theme": "ch2_theoretical_framework", "source": "openalex"}
{"key": "chadee2023", "title": "Reducing Cost Overrun in Public Housing Projects: A Simplified Reference Class Forecast for Small Island Developing States", "authors": ["Aaron Chadee", "Hector Martin", "Sihara Gallage", "Upaka Rathnayake"], "year": 2023, "venue": "Buildings", "doi": "10.3390/buildings13040998", "url": "https://doi.org/10.3390/buildings13040998", "abstract": "<jats:p>Inaccuracies in cost estimation on construction projects is a contested topic in praxis. Among the leading explanations for cost overrun (CO), factors accounting for large variances in actual cost are shown to have psychological or political roots. The context of public sector social housing projects (PSSHPs) in Small Island Developing States (SIDS) is positioned with similar CO challenges. This study is the fifth phase of a series of research projects on the vulnerability of PSSHPs to COs, and the need to de-risk cost estimates. The aim of this study is to present a simple and practical application of Reference Class Forecasting (RCF), a promising solution utilizing an “outside view” approach, as an effective control to reduce the variance of forecasted cost inaccuracies. Using a sample set of 82 housing projects, a reference class of 23 projects was selected based on properties such as design-build procurement type and local contractor involvement. A probability distribution was then established for this reference class, and required cost uplifts to be applied were based on the level of risk a housing agency is willing to accept for PSSHPs. Finally, the accuracy of the reference class was tested using a recently completed project. The results showed that the RCF method, based on a 50th percentile risk acceptance of CO, provides a closer estimate to the actual costs of the project as compared to the contracted costs. This empirical study is the first to undertake and implement RCF in the 52 SIDS and presents the first instance of practical RCF in public housing projects worldwide, thus providing a platform for improvement in future PSSHPs’ budget forecasting. The research can be applied to lessen societal and economic welfare losses as well as significant financial risks for governments. The implementation of practical safeguards, such as RCF, together with contemporary standard project controls, provides immediate advantages for enhancing accuracy in present forecasting approaches against financial risks. It allows for improved value derived from social infrastructure projects, improved supply of public housing, and consequently progress for these nations towards achieving their sustainable development goals.</jats:p>", "grade": "A", "theme": "ch2_theoretical_framework", "source": "crossref"}
{"key": "awojobi2016", "title": "Managing the cost overrun risks of hydroelectric dams: An application of reference class forecasting techniques", "authors": ["Omotola Awojobi", "Glenn P. Jenkins"], "year": 2016, "venue": "Renewable and Sustainable Energy Reviews", "doi": "10.1016/j.rser.2016.05.006", "url": "https://doi.org/10.1016/j.rser.2016.05.006", "abstract": null, "grade": "A", "theme": "ch2_theoretical_framework", "source": "crossref"}
{"key": "austin2022", "title": "Estimation of the Absolute Risk of Cardiovascular Disease and Other Events: Issues With the Use of Multiple Fine-Gray Subdistribution Hazard Models", "authors": ["P. Austin", "H. Putter", "Douglas S. Lee", "E. Steyerberg"], "year": 2022, "venue": "Circulation. Cardiovascular Quality and Outcomes", "doi": "10.1161/circoutcomes.121.008368", "url": "https://doi.org/10.1161/circoutcomes.121.008368", "abstract": "Supplemental Digital Content is available in the text. Background: The Fine-Gray subdistribution hazard model is frequently used in the cardiovascular literature to estimate subject-specific probabilities of the occurrence of an event of interest over time in the presence of competing risks. A little-known limitation of this approach is that, for some subjects and for some time points, the sum of the subject-specific probabilities for the different event types (eg, cardiovascular and noncardiovascular death) can exceed one. Methods: We used data on 8238 patients hospitalized with congestive heart failure in Ontario, Canada. We fit 2 Fine-Gray subdistribution hazards models, one for cardiovascular death and one for noncardiovascular death and estimated the probability of death due to each cause within 5 years of hospital admission. We also fit 2 cause-specific hazard models for the 2 event types and combined the estimated cause-specific hazard functions to obtain subject-specific estimates of the probabilities of each of the 2 event types occurring within 5 years. Results: When adding the probabilities of 5-year cardiovascular death and 5-year noncardiovascular death obtained from the Fine-Gray subdistribution hazard models, 8.6% of subjects had an estimated probability of 5-year all-cause mortality that exceeded 1 (100%). This problem was avoided by fitting 2 cause-specific hazard models, one for each outcome type, and combining the estimated cause-specific hazard functions to obtain subject-specific estimates of the risk of cardiovascular and noncardiovascular death. Conclusions: The Fine-Gray subdistribution hazard model may be problematic to use for a comprehensive assessment of absolute risks of multiple outcomes, while the combination of 2 cause-specific hazard models shows better statistical behaviour. Cause-specific modeling should not be discarded in competing risk situations.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "semanticscholar"}
{"key": "li2019", "title": "An Additive-Multiplicative Cox-Aalen Subdistribution Hazard Model for Competing Risks Data", "authors": ["Wanxing Li", "Yonghong Long"], "year": 2019, "venue": "Journal of Systems Science and Complexity", "doi": "10.1007/s11424-019-7281-6", "url": "https://doi.org/10.1007/s11424-019-7281-6", "abstract": null, "grade": "A", "theme": "ch2_theoretical_framework", "source": "crossref"}
{"key": "lovallo2023", "title": "Governing Large Projects: A Three-Stage Process to Get It Right", "authors": ["Dan Lovallo", "Matteo Cristofaro", "Bent Flyvbjerg"], "year": 2023, "venue": "Academy of Management Perspectives", "doi": "10.5465/amp.2021.0129", "url": "https://openalex.org/W4353092949", "abstract": "Private and public megaprojects, whether new plant facilities, IT systems, skyscrapers, airports, railways, roads, or the Olympics, are frequently associated with dramatic cost and schedule overruns. The root causes are behavioral biases – such as optimism and deliberate deception – accompanied by principal-agent issues and a lack of project-related skills. Through a three-stage process – i.e., Forecasting, Organizing, and Executing (FOX) – we organize and offer solutions to mitigate the cognitive biases and agency issues planners and policymakers face in large projects. Following the three-stage FOX process and building on Behavioral Decision Theory (BDT), we first review evidence for the accuracy of Reference Class Forecasting (RCF), which considers comparable past projects to forecast a current, planned project. We provide evidence for RCF performance and recent methodological extensions such as Similarity Based Forecasting (SBF). Second, considering the principal-agent and project governance literature, we offer organizational solutions to reduce unfounded optimism and deception, including debiasing techniques and specific measures to curb principal-agent issues. Third, we sugg", "grade": "A", "theme": "ch2_theoretical_framework", "source": "openalex"}
{"key": "natarajan2022", "title": "Reference Class Forecasting and Machine Learning for Improved Offshore Oil and Gas Megaproject Planning: Methods and Application", "authors": ["Ananth Natarajan"], "year": 2022, "venue": "Project Management Journal", "doi": "10.1177/87569728211045889", "url": "https://doi.org/10.1177/87569728211045889", "abstract": "<jats:p> This article develops and describes rigorous oil and gas project forecasting methods. First, it builds a theoretical foundation by mapping megaproject performance literature to these projects. Second, it draws on heuristics and biases literature, using a questionnaire to demonstrate forecasting-related biases and principal-agent issues among industry project professionals. Third, it uses methodically collected project performance data to demonstrate that overrun distributions are non-normal and fat-tailed. Fourth, reference-class forecasting is demonstrated for cost and schedule uplifts. Finally, a predictive approach using machine learning (ML) considers project-specific factors to forecast the most likely cost and schedule overruns in a project. </jats:p>", "grade": "A", "theme": "ch2_theoretical_framework", "source": "crossref"}
{"key": "chadee2021", "title": "The Influence of Optimism Bias on Time and Cost on Construction Projects", "authors": ["Aaron Anil Chadee", "Salisha R. Hernandez", "Héctor Martín"], "year": 2021, "venue": "Emerging Science Journal", "doi": "10.28991/esj-2021-01287", "url": "https://openalex.org/W3188060420", "abstract": "The unresolved scholarly debate to curtail cost and time performances in projects has led to alternate solutions, departing from the dominant technical school of thought to include concepts from behavioural sciences. In this paper, we consider the psychological effect, namely optimism bias, as one of the root causes for delays in cost overruns on projects. The research objectives were to determine the level of bias among project participants, rank time and cost overrun causes according to the participants’ bias score and establish a mitigation strategy to curb potential delays and cost overrun impacts based on the bias scores obtained. A literature survey was conducted to determine causal factors contributing to delays and cost overruns linked to optimism bias. Through a pilot survey of three semi-structured interviews, eighty factors obtained from the literature survey were reduced to 24 critical delay and cost overrun factors relevant to Trinidad and Tobago. A questionnaire was subsequently developed seeking construction professionals to rate their bias scores based on an 11-point Likert scale. The research confirms that project planners and decision-makers exhibit moderate level", "grade": "A", "theme": "ch2_theoretical_framework", "source": "openalex"}
{"key": "chen2023", "title": "Toward a Deeper Understanding of Optimism Bias and Transport Project Cost Overrun", "authors": ["Yizi Chen", "Dominic D. Ahiaga-Dagbui", "Muhammad Jamaluddin Thaheem", "Asheem Shrestha"], "year": 2023, "venue": "Project Management Journal", "doi": "10.1177/87569728231180268", "url": "https://doi.org/10.1177/87569728231180268", "abstract": "<jats:p> There is a growing face-value acceptance of optimism bias as the primary cause of transport cost overruns. This article provides a timely review of literature on optimism bias and transport infrastructure project cost overruns. The article identifies significant gaps and unanswered questions about the relationship between optimism bias in project cost appraisal and cases of transport infrastructure cost overruns. The presence and nature of optimism bias in the complex institutional environment of project cost appraisal are largely understudied and not well understood. Consequently, this has significant implications for the development of effective mitigation strategies for improving transport project cost performance. </jats:p>", "grade": "A", "theme": "ch2_theoretical_framework", "source": "crossref"}
{"key": "zhang2010", "title": "SAS macros for estimation of direct adjusted cumulative incidence curves under proportional subdistribution hazards models", "authors": ["Xu Zhang", "Mei‐Jie Zhang"], "year": 2010, "venue": "Computer Methods and Programs in Biomedicine", "doi": "10.1016/j.cmpb.2010.07.005", "url": "https://openalex.org/W1977455450", "abstract": null, "grade": "A", "theme": "ch2_theoretical_framework", "source": "openalex"}
{"key": "li2017b", "title": "An additive subdistribution hazard model for competing risks data", "authors": ["Wanxing Li", "Xiaoming Xue", "Yonghong Long"], "year": 2017, "venue": "Communications in Statistics - Theory and Methods", "doi": "10.1080/03610926.2016.1277759", "url": "https://doi.org/10.1080/03610926.2016.1277759", "abstract": null, "grade": "A", "theme": "ch2_theoretical_framework", "source": "crossref"}
{"key": "dixon2011", "title": "A competing risks model for correlated data based on the subdistribution hazard", "authors": ["Stephanie N. Dixon", "Gerarda A. Darlington", "Anthony F. Desmond"], "year": 2011, "venue": "Lifetime Data Analysis", "doi": "10.1007/s10985-011-9198-9", "url": "https://doi.org/10.1007/s10985-011-9198-9", "abstract": null, "grade": "A", "theme": "ch2_theoretical_framework", "source": "crossref"}
{"key": "zhang2019", "title": "Fine–Gray proportional subdistribution hazards model for competing risks data under length-biased sampling", "authors": ["Feipeng Zhang", "Heng Peng", "Yong Zhou"], "year": 2019, "venue": "Statistics and Its Interface", "doi": "10.4310/sii.2019.v12.n1.a10", "url": "https://doi.org/10.4310/sii.2019.v12.n1.a10", "abstract": null, "grade": "A", "theme": "ch2_theoretical_framework", "source": "crossref"}
{"key": "chaisemartin2023", "title": "Two-Way Fixed Effects and Difference-in-Differences Estimators with Heterogeneous Treatment Effects and Imperfect Parallel Trends", "authors": ["Clément de Chaisemartin", "Xavier d'Haultfoeuille"], "year": 2023, "venue": "SSRN Electronic Journal", "doi": "10.2139/ssrn.4487202", "url": "https://doi.org/10.2139/ssrn.4487202", "abstract": null, "grade": "B", "theme": "ch2_theoretical_framework", "source": "crossref"}
{"key": "vilsmeier2026", "title": "The choice of time scales in survival analysis has implications: calendar time versus patients’ time-to-event", "authors": ["J. Vilsmeier", "Gisela Büchele", "M. Rehm", "Theresa Unseld", "D. Rothenbacher", "J. Beyersmann"], "year": 2026, "venue": "BMC Medical Research Methodology", "doi": "10.1186/s12874-026-02884-3", "url": "https://doi.org/10.1186/s12874-026-02884-3", "abstract": "In the EvaCoM project, a retrospective cohort study of Germany-wide health insurance data of 29607 geriatric patients with fractures, the use of different time scales led to contradicting estimates in the Cox proportional hazards model. Here, the impact of quality audit, resulting in certification, of healthcare providers was of interest, with possible time scales being calendar time in which the audit acts or a patient’s time-to-event. For the analysis the patients were divided into groups depending on whether the certification occurred before or after the patient’s hospitalization, which adds a temporal component to the intervention (treatment in a certified hospital or not). A Cox model in calendar time found a harmful association of the audit with mortality (hazard ratio (HR) 1.13; 95% CI [1.04-1.23]), but in “time since hospital admission” no significant association was found (HR 1.04 [0.99-1.10]). To investigate these contradictions, the hazards in “time since hospital admission” are parametrically approximated with piecewise linear functions and transformed to calendar time by deriving patient-specific hazards based on their hospital admission date. A Poisson regression with both time scales simultaneously is used to investigate the contradictory results further. Matching is used to analyse the association in calendar time without using an additional time scale. The analysis of the approximated and transformed hazards leads to the conclusion that using calendar time causes a structural bias, because, in calendar time, patients of the pre-certification group enter the study earlier than those in the post-certification group. In combination with time-dependent and decreasing hazards, this leads to an artificial increase of the hazard ratio. A Poisson regression using both time scales (HR 1.00 [0.92-1.08]) and a Cox regression on matched data (HR 0.99 [0.90-1.09]) confirmed this result, finding no significant association between audits and mortality. In EvaCoM, the estimation of significant association in calendar time is a consequence of a structural bias caused by patients being shifted in calendar time and not a true harmful effect. The choice of time scale may severely impact the results. We present methods to disentangle the effects of different time scales.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "semanticscholar"}
{"key": "latouche2013", "title": "A competing risks analysis should report results on all cause-specific hazards and cumulative incidence functions", "authors": ["Aurélien Latouche", "Arthur Allignol", "Jan Beyersmann", "Myriam Labopin", "Jason P. Fine"], "year": 2013, "venue": "Journal of Clinical Epidemiology", "doi": "10.1016/j.jclinepi.2012.09.017", "url": "https://openalex.org/W2020152925", "abstract": null, "grade": "A", "theme": "ch2_theoretical_framework", "source": "openalex"}
{"key": "flyvbjerg2007b", "title": "Curbing Optimism Bias and Strategic Misrepresentation in Planning: Reference Class Forecasting in Practice", "authors": ["Bent Flyvbjerg"], "year": 2007, "venue": "European Planning Studies", "doi": "10.1080/09654310701747936", "url": "https://openalex.org/W2171158391", "abstract": "Absract The American Planning Association recently endorsed a new forecasting method called reference class forecasting, which is based on theories of planning and decision-making that won the 2002 Nobel prize in economics. This paper details the method and describes the first instance of reference class forecasting in planning practice. First, the paper documents that inaccurate projections of costs, demand, and other impacts of plans are a major problem in planning. Second, the paper explains inaccuracy in terms of optimism bias and strategic misrepresentation. Third, the theoretical basis is presented for reference class forecasting, which achieves accuracy in projections by basing them on actual performance in a reference class of comparable actions and thereby bypassing both optimism bias and strategic misrepresentation. Fourth, the paper presents the first case of practical reference class forecasting, which concerns cost projections for planning of large transportation infrastructure investments in the UK, including the Edinburgh Tram and London's £15 billion Crossrail project. Finally, potentials for and barriers to reference class forecasting are assessed.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "openalex"}
{"key": "flyvbjerg2004", "title": "Procedures for Dealing with Optimism Bias in Transport Planning: Guidance Document", "authors": ["Bent Flyvbjerg", "Carsten Glenting", "Arne Rønnest"], "year": 2004, "venue": "VBN Forskningsportal (Aalborg Universitet)", "doi": null, "url": "https://openalex.org/W2739390026", "abstract": "The UK Treasury (HM Treasury) has noted there is a demonstrated, systematic, tendency for project appraisers to be overly optimistic and that to redress this tendency appraisers should make explicit, empirically based adjustments to the estimates of a project&#39;s costs, benefits, and duration. HM Treasury recommends that these adjustments be based on data from past projects or similar projects elsewhere, and adjusted for the unique characteristics of the project in hand. In response to this, the UK Department for Transport (DfT), has produced the present Guidance Document. The main aims of the document are to provide empirically based optimism bias up-lifts for selected reference classes of transport infrastructure projects and provide guidance on using the established uplifts to produce more realistic forecasts for the individual project&#39;s capital expenditures. Furthermore, the underlying causes and institutional context for optimism bias in British transport projects are discussed and some possibilities for reducing optimism bias in project preparation and decision-making are identified.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "openalex"}
{"key": "flyvbjerg2016", "title": "Reference class forecasting for Hong Kong’s major roadworks projects", "authors": ["Bent Flyvbjerg", "Chi-keung Hon", "Wing Huen Fok"], "year": 2016, "venue": "Proceedings of the Institution of Civil Engineers - Civil Engineering", "doi": "10.1680/jcien.15.00075", "url": "https://openalex.org/W2525433628", "abstract": "Reference class forecasting is a method to remove optimism bias and strategic misrepresentation in infrastructure projects and programmes. In 2012 the Hong Kong government’s Development Bureau commissioned a feasibility study on reference class forecasting in Hong Kong – a first for the Asia-Pacific region. This study involved 25 roadwork projects, for which forecast costs and durations were compared with actual outcomes. The analysis established and verified the statistical distribution of the forecast accuracy at various stages of project development, and benchmarked the projects against a sample of 863 similar projects. The study contributed to the understanding of how to improve forecasts by de-biasing early estimates, explicitly considering the risk appetite of decision makers, and safeguarding public funding allocation by balancing exceedance and under-use of project budgets.", "grade": "A", "theme": "ch2_theoretical_framework", "source": "openalex"}
{"key": "dubos2008", "title": "Technology Readiness Level, Schedule Risk, and Slippage in Spacecraft Design", "authors": ["G. F. Dubos", "J. H. Saleh", "R. Braun"], "year": 2008, "venue": "Journal of Spacecraft and Rockets", "doi": "10.2514/1.34947", "url": "https://doi.org/10.2514/1.34947", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "seed"}
{"key": "dubos2007conf", "title": "Technology Readiness Level, Schedule Risk and Slippage in Spacecraft Design: Data Analysis and Modeling (conference antecedent)", "authors": ["G. F. Dubos", "J. H. Saleh", "R. Braun"], "year": 2007, "venue": "AIAA SPACE Conference", "doi": "10.2514/6.2007-6020", "url": "https://doi.org/10.2514/6.2007-6020", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "seed"}
{"key": "bearden2004", "title": "Complexity based cost estimating relationships for space systems", "authors": ["D. A. Bearden"], "year": 2004, "venue": "2004 IEEE Aerospace Conference", "doi": "10.1109/aero.2004.1368229", "url": "https://doi.org/10.1109/aero.2004.1368229", "abstract": "As cost estimating methods evolve and grow increasingly important in the lifecycle of complex engineering feats, effective cost analysis methods are finding their way into the early system level design phases. What follows outlines and how to develop a parametrically determined cost estimating relationship (CER) that can be used to support the system design tradeoffs that take place throughout the study and development phases of space systems project. There are three steps in building a CCER. First, the key technical elements that determine the complexity of the subsystem are hypothesized; secondly, the elements are ranked with respect to the characteristics of the same class in our historical database; finally, all individual ranks are combined to quantify the overall subsystem complexity. At this point the systems engineer must make use of his or her experience and expertise to verify the results given by the CCER by answering the following questions, among others: was subsystem A more complex than subsystem B? If so did it affect costs accordingly? What about the schedule or time lapse to complete the product? How did these three parameters interact? Once the CCER answers the ab", "grade": "A", "theme": "ch3_literature_review", "source": "seed"}
{"key": "flyvbjerg2005", "title": "How (In)accurate Are Demand Forecasts in Public Works Projects? The Case of Transportation", "authors": ["B. Flyvbjerg", "M. K. Skamris Holm", "S. L. Buhl"], "year": 2005, "venue": "Journal of the American Planning Association", "doi": "10.1080/01944360508976688", "url": "https://doi.org/10.1080/01944360508976688", "abstract": "This article presents results from the first statistically significant study of traffic forecasts in transportation infrastructure projects. The sample used is the largest of its kind, covering 210 projects in 14 nations worth US$59 billion. The study shows with very high statistical significance that forecasters generally do a poor job of estimating the demand for transportation infrastructure projects. The result is substantial downside financial and economic risks. Such risks are typically ignored or downplayed by planners and decision makers, to the detriment of social and economic welfare. For nine out of ten rail projects passenger forecasts are overestimated; average overestimation is 106 percent. This results in large benefit shortfalls for rail projects. For half of all road projects the difference between actual and forecasted traffic is more than 20 percent. Forecasts have not become more accurate over the 30-year period studied. If techniques and skills for arriving at accurate demand forecasts have improved over time, as often claimed by forecasters, this does not show in the data. The causes of inaccuracy in forecasts are different for rail and road projects, with pol", "grade": "A", "theme": "ch3_literature_review", "source": "seed"}
{"key": "railroads", "title": "Railroads and American Economic Growth: Essays in Econometric History (Fogel 1964)", "authors": [], "year": null, "venue": null, "doi": "10.2307/2552284", "url": "https://doi.org/10.2307/2552284", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "hall-of-shoulders:fogel"}
{"key": "railroadsb", "title": "Railroads and American Economic Growth: A Market Access Approach (Donaldson & Hornbeck 2013)", "authors": [], "year": null, "venue": null, "doi": "10.3386/w19213", "url": "https://doi.org/10.3386/w19213", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "hall-of-shoulders:fogel"}
{"key": "railroadsc", "title": "Railroads, Reallocation, and the Rise of American Manufacturing (2019)", "authors": [], "year": null, "venue": null, "doi": "10.3386/w26594", "url": "https://doi.org/10.3386/w26594", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "hall-of-shoulders:fogel"}
{"key": "railroad", "title": "Railroad Impact in Backward Economies: Spain, 1850-1913 (Herranz-Loncan 2006)", "authors": [], "year": null, "venue": null, "doi": "10.1017/s0022050706000350", "url": "https://doi.org/10.1017/s0022050706000350", "abstract": null, "grade": "B", "theme": "ch3_literature_review", "source": "hall-of-shoulders:fogel"}
{"key": "economic", "title": "Economic Benefits of the Global Positioning System (GPS) to the U.S. Private Sector (RTI International for NIST, 2019)", "authors": [], "year": null, "venue": null, "doi": "10.6028/nist.gcr.25-062", "url": "https://doi.org/10.6028/nist.gcr.25-062", "abstract": null, "grade": "B", "theme": "ch3_literature_review", "source": "hall-of-shoulders:fogel"}
{"key": "an", "title": "An evaluation of dependencies of critical infrastructure timing systems on the Global Positioning System (GPS) (NIST 2021)", "authors": [], "year": null, "venue": null, "doi": "10.6028/nist.tn.2189", "url": "https://doi.org/10.6028/nist.tn.2189", "abstract": null, "grade": "B", "theme": "ch3_literature_review", "source": "hall-of-shoulders:fogel"}
{"key": "orbital", "title": "Orbital debris and the market for satellites (Rao 2023)", "authors": [], "year": null, "venue": null, "doi": "10.1016/j.ecolecon.2023.107831", "url": "https://doi.org/10.1016/j.ecolecon.2023.107831", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "hall-of-shoulders:fogel"}
{"key": "opus", "title": "OPUS: An Integrated Assessment Model for Satellites and Orbital Debris (2023)", "authors": [], "year": null, "venue": null, "doi": "10.48550/arxiv.2309.10252", "url": "https://doi.org/10.48550/arxiv.2309.10252", "abstract": null, "grade": "B", "theme": "ch3_literature_review", "source": "hall-of-shoulders:fogel"}
{"key": "space", "title": "Space, the Final Economic Frontier (Weinzierl 2018)", "authors": [], "year": null, "venue": null, "doi": "10.1257/jep.32.2.173", "url": "https://doi.org/10.1257/jep.32.2.173", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "hall-of-shoulders:fogel"}
{"key": "satellite", "title": "Satellite launch traffic forecast based on the global Gross Domestic Product and constellation plans (Retagne & Colombo 2026)", "authors": [], "year": null, "venue": null, "doi": "10.1016/j.actaastro.2026.04.046", "url": "https://doi.org/10.1016/j.actaastro.2026.04.046", "abstract": null, "grade": "B", "theme": "ch3_literature_review", "source": "hall-of-shoulders:fogel"}
{"key": "spaceb", "title": "Space sustainability rating: Designing a composite indicator to incentivize satellite operators to pursue long-term sustainability of the space environment (Rathnasabapathy et al. 2025)", "authors": [], "year": null, "venue": null, "doi": "10.1016/j.actaastro.2025.03.034", "url": "https://doi.org/10.1016/j.actaastro.2025.03.034", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "hall-of-shoulders:fogel"}
{"key": "pretest", "title": "Pretest with Caution: Event-Study Estimates after Testing for Parallel Trends", "authors": [], "year": null, "venue": null, "doi": "10.1257/aeri.20210236", "url": "https://doi.org/10.1257/aeri.20210236", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "hall-of-shoulders:callaway_santanna"}
{"key": "evaluating", "title": "Evaluating the impact of space activities in low earth orbit", "authors": [], "year": null, "venue": null, "doi": "10.1016/j.actaastro.2021.03.030", "url": "https://doi.org/10.1016/j.actaastro.2021.03.030", "abstract": null, "grade": "B", "theme": "ch3_literature_review", "source": "hall-of-shoulders:callaway_santanna"}
{"key": "evaluatingb", "title": "Evaluating the environmental impact of space missions", "authors": [], "year": null, "venue": null, "doi": "10.1016/j.actaastro.2025.06.024", "url": "https://doi.org/10.1016/j.actaastro.2025.06.024", "abstract": null, "grade": "B", "theme": "ch3_literature_review", "source": "hall-of-shoulders:callaway_santanna"}
{"key": "tipping", "title": "Tipping Points of Space Debris in Low Earth Orbit", "authors": [], "year": null, "venue": null, "doi": "10.5334/ijc.1275", "url": "https://doi.org/10.5334/ijc.1275", "abstract": null, "grade": "B", "theme": "ch3_literature_review", "source": "hall-of-shoulders:callaway_santanna"}
{"key": "impact", "title": "Impact of Rocket Launch and Space Debris Air Pollutant Emissions on Stratospheric Ozone and Global Climate", "authors": [], "year": null, "venue": null, "doi": "10.1029/2021ef002612", "url": "https://doi.org/10.1029/2021ef002612", "abstract": null, "grade": "B", "theme": "ch3_literature_review", "source": "hall-of-shoulders:callaway_santanna"}
{"key": "the", "title": "The environmental impact of emissions from space launches: A comprehensive review", "authors": [], "year": null, "venue": null, "doi": "10.1016/j.jclepro.2020.120209", "url": "https://doi.org/10.1016/j.jclepro.2020.120209", "abstract": null, "grade": "B", "theme": "ch3_literature_review", "source": "hall-of-shoulders:callaway_santanna"}
{"key": "actaflight_spares_2019", "title": "A cost effective methodology for building flight spares for robotic life extension", "authors": [], "year": 2019, "venue": "Acta Astronautica", "doi": "10.1016/j.actaastro.2019.06.025", "url": "https://doi.org/10.1016/j.actaastro.2019.06.025", "abstract": "Cost-effective flight-spares methodology, relevant to heritage build and development cost-time trends.", "grade": "A", "theme": "ch3_literature_review", "source": "brain:acta-papers"}
{"key": "actatech_roadmap_2022", "title": "Technology roadmapping methodology for future transportation systems", "authors": [], "year": 2022, "venue": "Acta Astronautica", "doi": "10.1016/j.actaastro.2022.03.038", "url": "https://doi.org/10.1016/j.actaastro.2022.03.038", "abstract": "Technology readiness and roadmapping methodology relevant to TRL-driven schedule risk for first-of-kind systems.", "grade": "A", "theme": "ch3_literature_review", "source": "brain:acta-papers"}
{"key": "behdinan2021", "title": "CARDINAL WTRL: TECHNOLOGY MATURITY, SCHEDULE SLIPPAGE AND TREND FORECASTING.", "authors": ["K. Behdinan", "S. Mishra"], "year": 2021, "venue": "Proceedings of the Design Society", "doi": "10.1017/pds.2021.60", "url": "https://doi.org/10.1017/pds.2021.60", "abstract": "Maturity assessments of technology is a crucial process to identify and acquire compatible technologies for a system’s development. However, being a complex and highly subjective process, the Government Accountability Office (GAO) has reported cost overruns and schedule slippages through the years. This study provides a unique Weighted Technology Readiness Level (WTRL) framework which utilizes cardinal factors to ascertain the maturity, schedule and trend of NASA’s 7 Technologies based on their maturity time. The framework utilizes MCDM methods to determine the cardinal complexity of each TRL. It allows the assimilation of other cardinal factors using a simple, open structure to track the overall technology maturity and readiness. Furthermore, this study highlights the importance of tailored TRL frameworks to determine the accurate cardinal coefficient of the said technology and the inferences derived otherwise. It eliminates several limitations of previous frameworks and compares against their performance using a verified statistical representation of processed data.", "grade": "A", "theme": "ch3_literature_review", "source": "semanticscholar"}
{"key": "k1998", "title": "The JPL Advanced Projects Design Team's Spacecraft Instrument Cost Model: an Objective, Multivariate Approach", "authors": ["Warfield, K.", "Roust, K."], "year": "1998", "venue": "NASA Technical Reports Server", "doi": null, "url": "https://ntrs.nasa.gov/citations/20060034648", "abstract": "This paper describes the development of a new satellite instrument cost model currently in use with the Jet Propulsion Laboratory's Advanced Projects Design Team.", "grade": "B", "theme": "ch3_literature_review", "source": "ntrs"}
{"key": "probabilistic2025", "title": "Probabilistic Cost-Schedule Risk Analysis in Offshore Construction Projects Using Monte Carlo Simulation and Quantitative Assessment", "authors": [], "year": 2025, "venue": "International Journal of Business and Technology Management", "doi": "10.55057/ijbtm.2025.7.9.34", "url": "https://doi.org/10.55057/ijbtm.2025.7.9.34", "abstract": "<jats:p>Offshore construction projects are frequently subject to considerable schedule delays and cost overruns, driven by technical complexity, environmental unpredictability, and market fluctuations. Traditional deterministic approaches often fail to capture these risks, offering limited value for decision-making in high-risk project settings. This study applies an integrated probabilistic approach by combining Schedule Risk Analysis (SRA) and Cost Risk Analysis (CRA) across three offshore case studies: (i) wellhead platform developments, (ii) a Very Low Abandonment Pressure (VLAP) project, and (iii) a brownfield Teja–Pepulut (TePu) development. Monte Carlo simulations were utilized to account for both aleatory and epistemic uncertainties, generate probabilistic estimates (P10, P50, P90), and identify key risk contributors. The findings reveal consistent discrepancies between deterministic plans and probabilistic results. Schedule outcomes at both the P50 and P90 levels were regularly exceeded, showing a systematic underestimation of schedule risks. Cost analysis also indicated increased contingency requirements, with hook-up and commissioning (HUC) activities identified as the most significant contributors. Additional cost exposure was linked to contractor performance limitations and volatile market conditions. While risk profiles varied across projects, deterministic models consistently underestimated the proper level of uncertainty. The study highlights the significance of probabilistic techniques in offshore project planning, offering practical insights into contingency allocation, contractor evaluation, and resource optimization in complex marine environments.</jats:p>", "grade": "A", "theme": "ch3_literature_review", "source": "crossref"}
{"key": "brown2024", "title": "Reference Class Forecasting and Its Application to Fusion Power Plant Cost Estimates", "authors": ["C. Brown", "Hanni Lux", "James R. Cowan"], "year": 2024, "venue": "IEEE Transactions on Plasma Science", "doi": "10.1109/tps.2024.3405631", "url": "https://doi.org/10.1109/tps.2024.3405631", "abstract": "Developments in fusion energy technology and the aspiration to build and run commercial fusion energy power plants have seen the commencement of numerous publicly and privately funded projects in recent years. Megaprojects, like fusion power plants, by their very nature are inherently complex and risky, therefore, providing a robust cost estimate in the early stages is challenging. In the fusion sector, this is amplified by the fact that very little data exist on which to base an estimate due to the novel nature of the materials and technologies involved. A common phenomenon during the estimating phase of a new project is the concept of optimism bias (OB), where underestimation of time, cost, and risk can cause impacts on the baseline cost and schedule, leading to significant over-runs during the project lifetime. Reference class forecasting (RCF) is a method used to mitigate against these factors, based on using actual performance data in a reference class of comparable projects to improve forecasting accuracy. This article will discuss RCF, how it has been used in recent megaprojects, and how it is intended to be used in the Spherical Tokamak for Energy Production (STEP) program to provide a full program cost model for a prototype fusion energy plant.", "grade": "A", "theme": "ch3_literature_review", "source": "semanticscholar"}
{"key": "hahn2020", "title": "Cost Estimation of Electronic Parts in NASA Space Missions", "authors": ["Meagan Hahn", "Rachel Sholder"], "year": 2020, "venue": "IEEE Aerospace Conference", "doi": "10.1109/aero47225.2020.9172574", "url": "https://doi.org/10.1109/aero47225.2020.9172574", "abstract": "This paper provides a cost model to develop early estimates for electronics, electrical, and electromechanical (EEE) parts costs during early design phases for instruments and spacecraft. Often, to support a certified proposal, the EEE parts group is required to generate a detailed cost estimate for instruments and spacecraft during preliminary design phases. This requires a premature development of a detailed bill of materials (BOM) far in advance of the final design and fabrication phases; it is therefore no surprise that EEE parts costs grow as a given design is refined and finalized and the required BOM is established. The aerospace cost estimating community lacks sufficient data and understanding of what contributes to EEE parts costs, which is becoming increasingly critical as many advanced instrument and spacecraft designs are relying more heavily on advanced electronics and field-programmable gate array (FPGA) development. This analysis seeks to identify several high-level parameters that can be identified early in the design phase (pre-Phase A through Phase C) to generate a realistic range of EEE parts. The resulting cost model can be used to inform the EEE parts estimating process, and provide program management with the potential cost range for appropriate reserve allocation. Actual costs of APL missions, instruments, and EEE parts are used. Technical leads provide the potential cost drivers as well as the technical data. These cost drivers (such as parts class, radiation, board area, and complexity of design and requirements) are investigated through multiple linear regression analysis. The regression results are used to develop cost estimating relationships (CERs) by determining the best predictors of EEE parts cost. It benefits the NASA and DoD cost communities to obtain a rough estimate of EEE cost during the design phase to more properly budget and provide a reasonable cost risk assessment.", "grade": "A", "theme": "ch3_literature_review", "source": "semanticscholar"}
{"key": "sobel2021", "title": "Effectiveness of Firm-Fixed Price Spacecraft Contracts to Curb Cost Growth", "authors": ["L. Sobel", "Elliott B. Tibor"], "year": 2021, "venue": "IEEE Aerospace Conference", "doi": "10.1109/aero50100.2021.9438356", "url": "https://doi.org/10.1109/aero50100.2021.9438356", "abstract": "There are many types of contracts used by NASA for science missions to procure spacecraft, this paper focuses on two main categories: Cost-Plus (CP) contracts and Firm-Fixed Price (FFP) contracts. When CP contracts are used, the government agrees to cover the actual expenses of the project which include the planned original cost and any additional labor or material costs incurred to complete the work. The CP contract mechanism is ideally implemented when government requirements are not well-defined, and the likelihood of a modification to the scope of the project is high. When FFP contracts are used, the government agrees to cover a non-variable cost and will not pay for any additional labor or material costs incurred to complete the work. The FFP contract mechanism is ideally implemented when the government requirements are well-defined, costs can be predicted, and the contractor has experience in manufacturing a product that fulfills the requirements. This paper investigates historical cost growth of spacecraft for a variety of NASA science missions launched over the last 20 years, by comparing historical cost growth of CP and FFP spacecraft from contract start to delivery. Additionally, this paper will also examine the potential causes of cost growth on FFP contracts, including schedule delays, requirement changes, the addition of new scope after the contract was signed, and mistakenly formulating a basis of estimate by assuming high heritage to a previous spacecraft. The results of this study will provide guidelines and lessons learned to help NASA and other government agencies determine when an FFP contract can be used effectively and efficiently.", "grade": "A", "theme": "ch3_literature_review", "source": "semanticscholar"}
{"key": "sholder2023", "title": "Math is EZIE: How Contracts Help Control Cost", "authors": ["Rachel Sholder", "S. Whitley"], "year": 2023, "venue": "IEEE Aerospace Conference", "doi": "10.1109/aero55745.2023.10115565", "url": "https://doi.org/10.1109/aero55745.2023.10115565", "abstract": "The aerospace cost estimating community relies on risk analyses to estimate confidence in a project's budget. At a NASA mission's preliminary design review (PDR), convention requires that baseline cost confidence plus project-held reserves should be around the 50th percentile and cost plus project-held reserves and unallocated future expenses (UFE) should be around the 70th percentile of the joint distribution of total cost and schedule. But how can we test whether our approach to determining 50th and 70th percentiles for missions going into PDR is reliable? An analysis of historical costs from past NASA missions shows that there is an 84 % chance that a mission will experience cost growth from PDR to Launch. At the empirical 50th and 70th percentiles, NASA missions are spending their full budgets plus 16% and 27 %, respectively. But does this change when we compare in-house spacecraft builds to contracted builds? As more commercial hardware options become available, NASA missions have relied on various cost contracts, particularly cost-plus (CP) contracts and firm-fixed-price contracts (FFP). In May 2022, the Electrojet Zeeman Imaging Explorer (EZIE), passed its PDR. EZIE is just one of many recent examples of NASA using commercially available hardware and FFP contract vehicles to control costs. With carefully designed science techniques that take advantage of commercial off the shelf (COTS) hardware from Blue Canyon Technologies, EZIE will be able to collect groundbreaking science for a lifecycle cost of $57.5M (FY22). To ensure the success of the EZIE mission, NASA must allocate and budget adequate funding. In this analysis, actual costs of NASA missions with contracted spacecraft are compared with actual costs of NASA missions with in-house builds. Comparisons are made between contract start estimate and final delivery costs. This paper will allow us to examine the NASA cost community's approach to reserve postures, particularly when contracts are employed. Using the empirical dataset as our guide, how can projects approaching PDR provide cost and schedule analysis that supports the goal of achieving 70% confidence in the budget at the portfolio level?", "grade": "A", "theme": "ch3_literature_review", "source": "semanticscholar"}
{"key": "hirshorn2016", "title": "Final Report of the NASA Technology Readiness Assessment (TRA) Study Team", "authors": ["Steven R. Hirshorn", "Sharon Jefferies"], "year": 2016, "venue": "NASA STI Repository (National Aeronautics and Space Administration)", "doi": null, "url": "https://openalex.org/W2739239624", "abstract": "The material in this report covers the results on the NASA-wide TRA team, who are responsible for ascertaining the full extent of issues and ambiguities pertaining to TRATRL and to provide recommendations for mitigation. The team worked for approximately 6 months to become knowledgeable on the current TRATRL process and guidance and to derive recommendations for improvement.The team reviewed the TRA processes of other government agencies (OGA), including international agencies, and found that while the high-level processes are similar, the NASA process has a greater level of detail. Finally, NASAs HQ OCT continues to monitor the GAOs efforts to produce a TRA Best Practices Guide, a draft of which was received in February 2016. This Guide could impact the recommendations of this report.", "grade": "B", "theme": "ch3_literature_review", "source": "openalex"}
{"key": "nilsen2023", "title": "Examining the Effects of Implementing Data-Driven Uncertainty in Cost Estimating Models", "authors": ["Victoria Nilsen"], "year": 2023, "venue": "IEEE Aerospace Conference", "doi": "10.1109/aero55745.2023.10116026", "url": "https://doi.org/10.1109/aero55745.2023.10116026", "abstract": "When conducting probabilistic cost analysis, correlation assumptions are key assumptions and often a driver for the total output or point estimate of a cost model. Although the National Aeronautics and Space Administration (NASA) has an entire community dedicated to the development of statistical cost estimating tools and techniques to manage program and project performance, the application of accurate and data-driven correlation coefficients within these models is often overlooked. Due to the uncertain nature of correlation between random variables, NASA has had difficulty quantifying the relationships between spacecraft subsystems with specific, data-driven correlation matrices. Previously, the NASA cost analysis community has addressed this challenge by either selecting a blanket correlation value to address uncertainty within the model or opting out of using any correlation value altogether. One hypothesized method of improving NASA cost estimates involves deriving subsystem correlation coefficients from the residuals of the regression equations for the cost estimating relationships (CERs) of various spacecraft subsystems and support functions. This paper investigates the feasibility of this methodology using the CERs from NASA's Project Cost Estimating Capability (PCEC) model. The correlation coefficients for each subsystem of the NASA Work Breakdown Structure were determined by correlating the residuals of PCEC's subsystem CERs. These correlation coefficients were then compiled into a 20x20 correlation matrix and were implemented into PCEC as an uncertainty factor influencing the model's pre-existing cost distributions. Once this correlation matrix was implemented into the cost distributions of PCEC, the Latin Hypercube Sampling function of the Microsoft Excel add-in Argo was used to simulate PCEC results for 40 missions within the PCEC database. These steps were repeated three additional times using the following correlation matrices: (1) a correlation matrix assuming the correlation between each subsystem is zero, (2) a correlation matrix assuming the correlation between each subsystem is 1, and (3) a correlation matrix using a blanket value of 0.3. The results of these simulations showed that the correlation matrix derived from the residuals of the subsystem CERs significantly reduced bias and error within PCEC's estimating capability. The results also indicated that the probability density function and cumulative distribution function of each mission in the PCEC database were altered significantly by the correlation matrices that were implemented into the model. This research produced (1) a standard subsystem correlation matrix that has been proven to improve estimating accuracy within PCEC and (2) a replicable methodology for creating this correlation matrix that can be used in future cost estimating models. This information can help the NASA cost analysis community understand the effects of applying uncertainty within cost models and perform sensitivity analyses on project cost estimates. This is significant because NASA has been frequently critiqued for underestimating project costs and this methodology has shown promise in improving NASA's future cost estimates and painting a more realistic picture of the total possible range of spacecraft development costs.", "grade": "A", "theme": "ch3_literature_review", "source": "semanticscholar"}
{"key": "bart2023", "title": "Estimating the Cost to Transition a Space System from Expendable to Reusable", "authors": ["Ryan de Freitas Bart", "K. Duda", "J. Hoffman"], "year": 2023, "venue": "IEEE Aerospace Conference", "doi": "10.1109/aero55745.2023.10115848", "url": "https://doi.org/10.1109/aero55745.2023.10115848", "abstract": "In recent years, the benefit of hardware reuse for space systems has been demonstrated in the launch market as reusable launch vehicles have enabled companies, primarily SpaceX with their Falcon 9 vehicle, to drive down launch costs prompting competitors to include reusability in their future designs to stay competitive. Although several reusable systems are currently being developed, the high cost and technical challenges of developing such systems remain an issue. To reduce these barriers, some organizations have chosen to first develop an expendable version of a system then transition it to a reusable version once the design has been proven. SpaceX used this approach when developing their Falcon 9 and Dragon vehicles with both starting as expendable systems which were transitioned to reusable after several successful missions. This approach allows for the benefits of creating an expendable design, relative simplicity and faster time to market, to be realized while still working towards a reusable vehicle. Although such an approach provides benefit, a significant drawback is the financial risk associated with developing two distinct versions of a system. Thus, there is a need for a method to optimize the design of an expendable space system, which will be transitioned to reusable, to minimize overall development cost. To realize this need, we propose a method to estimate the program development cost by estimating the cost to develop the initial expendable vehicle and the cost to transition it to reusable. This paper first discusses the primary considerations for modifying an expendable system for reuse, focusing on the hardware changes required. The methods used to estimate the initial expendable system cost and the transition cost are then discussed. The expendable system cost estimation uses cost estimating relationships and analogous cost estimating, which are modified by a change factor and technology readiness level growth factor depending on the design of each entity. A discount rate factor is also established for each reusable entity that is included in the expendable design to account for the time value of money and an inflation factor is used to convert to constant-year dollars. The transition cost is estimated by calculating the cost of each entity which is added to or modified from the expendable design. For reusable entities that are modified versions of entities used in the original expendable system, a reliability growth factor is applied to account for the increased reliability necessary for the reusable version. However, if the entity only exists in the reusable design, its cost is estimated using similar methods as for estimating the cost of the expendable system. An Integration & Test (I&T) factor is calculated for each entity added or modified when creating the reusable design to reflect the cost of integrating changes into the expendable design to make it reusable along with associated testing. In future work, this cost estimation methodology will be used in a multidisciplinary design optimization framework to calculate program life-cycle cost objective values for each space system evaluated.", "grade": "A", "theme": "ch3_literature_review", "source": "semanticscholar"}
{"key": "how", "title": "How Common Is Cost Overrun and Cost Growth?", "authors": [], "year": null, "venue": "Project Cost Overrun", "doi": "10.1017/9781316779675.007", "url": "https://doi.org/10.1017/9781316779675.007", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "crossref"}
{"key": "gelber1991", "title": "Cumulative incidence functions should replace integrated cause-specific hazard functions to describe probabilities of competing events over time", "authors": ["Richard D. Gelber", "Robert J. Gray"], "year": 1991, "venue": "Controlled Clinical Trials", "doi": "10.1016/0197-2456(91)90089-5", "url": "https://doi.org/10.1016/0197-2456(91)90089-5", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "crossref"}
{"key": "kipp2012", "title": "Impact of instrument schedule growth on mission cost and schedule growth for recent NASA missions", "authors": ["K. A. Kipp", "S. C. Ringler", "E. L. Chapman", "C. W. Freaner"], "year": 2012, "venue": "2012 IEEE Aerospace Conference", "doi": "10.1109/aero.2012.6187407", "url": "https://doi.org/10.1109/aero.2012.6187407", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "crossref"}
{"key": "bitten2018", "title": "The effect of policy changes on NASA science mission cost &amp; schedule growth", "authors": ["Robert Bitten", "Charles Hunt", "Debra Emmons", "Robert Kellogg", "Eric Mahr", "Sarah Lang"], "year": 2018, "venue": "2018 IEEE Aerospace Conference", "doi": "10.1109/aero.2018.8396408", "url": "https://doi.org/10.1109/aero.2018.8396408", "abstract": null, "grade": "A", "theme": "ch3_literature_review", "source": "crossref"}
{"key": "habibagahi2015", "title": "NASA Instrument Cost Model for Explorer-Like Mission Instruments (NICM-E)", "authors": ["H. Habib-agahi"], "year": 2015, "venue": "NASA Technical Reports Server", "doi": null, "url": "https://ntrs.nasa.gov/citations/20150008233", "abstract": null, "grade": "B", "theme": "ch4_data_and_measurement", "source": "seed"}
{"key": "habibagahi2019", "title": "NASA Space Flight Instruments: Cost-Time Trends", "authors": ["H. Habib-agahi"], "year": 2019, "venue": "NASA Technical Reports Server", "doi": null, "url": "https://ntrs.nasa.gov/citations/20190026811", "abstract": null, "grade": "B", "theme": "ch4_data_and_measurement", "source": "seed"}
{"key": "irons2012", "title": "The next Landsat satellite: The Landsat Data Continuity Mission", "authors": ["J. R. Irons", "J. L. Dwyer", "J. A. Barsi"], "year": 2012, "venue": "Remote Sensing of Environment", "doi": "10.1016/j.rse.2011.08.026", "url": "https://doi.org/10.1016/j.rse.2011.08.026", "abstract": "The Landsat program is one of the longest running satellite programs for Earth observations from space. The program was initiated by the launch of Landsat 1 in 1972. Since then a series of six more Landsat satellites were launched and at least one of those satellites has been in operations at all times to continuously collect images of the global land surface. The Department of Interior (DOI) U.S. Geological Survey (USGS) preserves data collected by all of the Landsat satellites at their Earth Resources Observation and Science (EROS) Center in Sioux Falls, South Dakota. This 40-year data archive provides an unmatched record of the Earth's land surface that has undergone dramatic changes in recent decades due to the increasing pressure of a growing population and advancing technologies. EROS provides the ability for anyone to search the archive and order digital Landsat images over the internet for free. The Landsat data are a public resource for observing, characterizing, monitoring, trending, and predicting land use change over time providing an invaluable tool for those addressing the profound consequences of those changes to society. The most recent launch of a Landsat satellite occurred in 1999 when Landsat 7 was placed in orbit. While Landsat 7 remains in operation, the National Aeronautics and Space Administration (NASA) and the DOI/ USGS are building its successor satellite system currently called the Landsat Data Continuity Mission (LDCM). NASA has the lead for building and launching the satellite that will carry two Earth-viewing instruments, the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS). The OLI will take images that measure the amount of sunlight reflected by the land surface at nine wavelengths of light with three of those wavelengths beyond the range of human vision. T1RS will collect coincident images that measure light emitted by the land surface as a function of surface temperature at two longer wavelengths well beyond the range of human vision. The DOI/USGS is developing the ground system that will command and control the LDCM satellite in orbit and manage the OLI and TIRS data transmitted by the satellite. DOI/USGS will thus operate the satellite and collect, archive, and distribute the image data as part of the EROS archive. DOI/USGS has committed to renaming LDCM as Landsat 8 following launch. By either name the satellite and its sensors will extend the 40-year archive with images sufficiently consistent with data from earlier Landsat satellites to allow multi-decadal, broad-area studies of our dynamic landscapes. The next Landsat satellite and ground system are on schedule for a January, 2013 launch.", "grade": "A", "theme": "ch4_data_and_measurement", "source": "seed"}
{"key": "what", "title": "What is value in the New Space Economy? The end-users' perspective on satellite data and solutions (Paravano, Locatelli & Trucco 2023)", "authors": [], "year": null, "venue": null, "doi": "10.1016/j.actaastro.2023.05.001", "url": "https://doi.org/10.1016/j.actaastro.2023.05.001", "abstract": null, "grade": "A", "theme": "ch4_data_and_measurement", "source": "hall-of-shoulders:fogel"}
{"key": "donaldson", "title": "The View from Above: Applications of Satellite Data in Economics", "authors": ["Dave Donaldson", "Adam Storeygard"], "year": null, "venue": null, "doi": "10.1257/jep.30.4.171", "url": "https://doi.org/10.1257/jep.30.4.171", "abstract": "The past decade or so has seen a dramatic change in the way that economists can learn by watching our planet from above. A revolution has taken place in remote sensing and allied fields such as computer science, engineering, and geography. Petabytes of satellite imagery have become publicly accessible at increasing resolution, many algorithms for extracting meaningful social science information from these images are now routine, and modern cloud-based processing power allows these algorithms to be run at global scale. This paper seeks to introduce economists to the science of remotely sensed data, and to give a flavor of how this new source of data has been used by economists so far and what might be done in the future.", "grade": "A", "theme": "ch4_data_and_measurement", "source": "hall-of-shoulders:callaway_santanna"}
{"key": "actaspaceborne_lidar_2023", "title": "Spacecraft and optics design considerations for a spaceborne lidar mission", "authors": [], "year": 2023, "venue": "Acta Astronautica", "doi": "10.1016/j.actaastro.2023.10.042", "url": "https://doi.org/10.1016/j.actaastro.2023.10.042", "abstract": "Design study of a spaceborne active lidar Earth-observation instrument, illustrating the first-of-kind active-sensor archetype whose technology maturity drives development schedule.", "grade": "A", "theme": "ch4_data_and_measurement", "source": "brain:acta-papers"}
{"key": "actaradiometer_tirs_2016", "title": "Dual-telescope multi-channel thermal-infrared radiometer for outer planet fly-by", "authors": [], "year": 2016, "venue": "Acta Astronautica", "doi": "10.1016/j.actaastro.2016.08.009", "url": "https://doi.org/10.1016/j.actaastro.2016.08.009", "abstract": "Thermal-infrared radiometer instrument design, illustrating the passive-radiometer archetype with heritage-driven development.", "grade": "A", "theme": "ch4_data_and_measurement", "source": "brain:acta-papers"}
{"key": "p2011", "title": "Utilization of Ancillary Data Sets for Conceptual SMAP Mission Algorithm Development and Product Generation", "authors": ["O'Neill, P.", "Podest, E."], "year": "2011", "venue": "NASA Technical Reports Server", "doi": null, "url": "https://ntrs.nasa.gov/citations/20150005750", "abstract": "The planned Soil Moisture Active Passive (SMAP) mission is one of the first Earth observation satellites being developed by NASA in response to the National Research Council's Decadal Survey, Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond [1]. Scheduled to launch late in 2014, the proposed SMAP mission would provide high resolution and frequent revisit global mapping of soil moisture and freeze/thaw state, utilizing enhanced Radio Frequency Interference (RFI) mitigation approaches to collect new measurements of the hydrological condition of the Earth's surface. The SMAP instrument design incorporates an L-band radar (3 km) and an L band radiometer (40 km) sharing a single 6-meter rotating mesh antenna to provide measurements of soil moisture and landscape freeze/thaw state [2]. These observations would (1) improve our understanding of linkages between the Earth's water, energy, and carbon cycles, (2) benefit many application areas including numerical weather and climate prediction, flood and drought monitoring, agricultural productivity, human health, and national security, (3) help to address priority questions on climate change, and (4) potentially provide continuity with brightness temperature and soil moisture measurements from ESA's SMOS (Soil Moisture Ocean Salinity) and NASA's Aquarius missions. In the planned SMAP mission prelaunch time frame, baseline algorithms are being developed for generating (1) soil moisture products both from radiometer measurements on a 36 km grid and from combined radar/radiometer measurements on a 9 km grid, and (2) freeze/thaw products from radar measurements on a 3 km grid. These retrieval algorithms need a variety of global ancillary data, both static and dynamic, to run the retrieval models, constrain the retrievals, and provide flags for indicating retrieval quality. The choice of which ancillary dataset to use for a particular SMAP product would be based on a number of factors, including its availability and ease of use, its inherent error and resulting impact on the overall soil moisture or freeze/thaw retrieval accuracy, and its compatibility with similar choices made by the SMOS mission. All decisions regarding SMAP ancillary data sources would be fully documented by the SMAP Project and made available to the user community.", "grade": "B", "theme": "ch4_data_and_measurement", "source": "ntrs"}
{"key": "moss2013", "title": "Parts quality management: Direct part marking of data matrix symbol for mission assurance", "authors": ["Chantrice Moss", "Suman Chakrabarti", "David W. Scott"], "year": 2013, "venue": null, "doi": "10.1109/aero.2013.6497372", "url": "https://openalex.org/W1968551854", "abstract": "A United States Government Accountability Office (GAO) review of twelve NASA programs found widespread parts quality problems contributing to significant cost overruns, schedule delays, and reduced system reliability. Direct part marking with Data Matrix symbols could significantly improve the quality of inventory control and parts lifecycle management. This paper examines the feasibility of using direct part marking technologies for use in future NASA programs. A structural analysis is based on marked material type, operational environment (e.g., ground, suborbital, Low Earth Orbit), durability of marks, ease of operation, reliability, and affordability. A cost-benefits analysis considers marking technology (label printing, data plates, and direct part marking) and marking types (two-dimensional machine-readable, human-readable). Previous NASA parts marking efforts and historical cost data are accounted for, including in-house vs. outsourced marking. Some marking methods are still under development. While this paper focuses on NASA programs, results may be applicable to a variety of industrial environments.", "grade": "B", "theme": "ch4_data_and_measurement", "source": "openalex"}
{"key": "park2021", "title": "Curbing cost overruns in infrastructure investment", "authors": ["Jung Eun Park"], "year": 2021, "venue": "European journal of transport and infrastructure research", "doi": "10.18757/ejtir.2021.21.2.5504", "url": "https://openalex.org/W3180083626", "abstract": "Infrastructure projects around the world have long been notorious for exceeding their budgets. To address persistent cost overruns, the American Planning Association urged planners to adopt reference class forecasting alongside traditional methods but the practice has not caught on in the U.S. Conversely, the U.K. adopted Kahneman’s Nobel Prize-winning theory to challenge biases in human judgment and mandated reference class forecasting for major projects in 2003. Has reference class forecasting, originally developed to rectify honest mistakes, brought the promised success in the public sector wherein political pressure is significant? Through before-and-after and with-and-without comparisons of 107 major projects, this empirical study examines the practical relevance of reference class forecasting for infrastructure investments. A before-and-after comparison reveals that the average cost overrun declined from 38% to 5% following the introduction of reference class forecasting. A with-and-without comparison also demonstrates that the U.K. surpassed its targeted probability of completing projects within budget by 12% using reference class forecasting, whereas the U.S. underperformed", "grade": "A", "theme": "ch4_data_and_measurement", "source": "openalex"}
{"key": "wulder2019", "title": "Current status of Landsat program, science, and applications", "authors": ["Michael A. Wulder", "Thomas R. Loveland", "David P. Roy", "Christopher J. Crawford", "Jeffrey G. Masek", "Curtis E. Woodcock", "Richard G. Allen", "Martha C. Anderson"], "year": 2019, "venue": "Remote Sensing of Environment", "doi": "10.1016/j.rse.2019.02.015", "url": "https://openalex.org/W2920930972", "abstract": "Formal planning and development of what became the first Landsat satellite commenced over 50 years ago in 1967. Now, having collected earth observation data for well over four decades since the 1972 launch of Landsat-1, the Landsat program is increasingly complex and vibrant. Critical programmatic elements are ensuring the continuity of high quality measurements for scientific and operational investigations, including ground systems, acquisition planning, data archiving and management, and provision of analysis ready data products. Free and open access to archival and new imagery has resulted in a myriad of innovative applications and novel scientific insights. The planning of future compatible satellites in the Landsat series, which maintain continuity while", "grade": "A", "theme": "ch4_data_and_measurement", "source": "openalex"}
{"key": "erb2025", "title": "1.02  NASA Earth Observations", "authors": ["Angela M Erb", "Peter B Boucher", "Miguel O Roman", "Ian L Paynter"], "year": "2025", "venue": "NASA Technical Reports Server", "doi": null, "url": "https://ntrs.nasa.gov/citations/20250010859", "abstract": "The NASA Earth Science Division (ESD) is part of the Science Mission Directorate and was established to advance understanding of Earth as an integrated system through space-based observations of Earth’s atmosphere, land, oceans, and biosphere. In the mid-late 1980s, the Earth Observing System (EOS) was conceived and implemented as a series of large “flagship” missions and smaller focused satellites, often in partnership with instruments and spacecraft from other nations and agencies. The EOS launched is first mission in 1999 and subsequently 9 additional missions highlighted in the first\nedition of this chapter. In the years since, NASA ESD has expanded its mission scope, science, and partnerships to include national, international, commercial, and academic partners in the quest to better understand our Home Planet and deliver decision-ready science-quality data that strengthens resilience, supports economic security, and guides effective Earth system management. These efforts safeguard the continuity of critical Earth System Data Records, which guide decisions related to long-term variability, extreme events, wildfire behavior, and global agricultural productivity among many other societal benefit areas.", "grade": "B", "theme": "ch4_data_and_measurement", "source": "ntrs"}
{"key": "feature2009", "title": "Feature Detection Systems Enhance Satellite Imagery", "authors": [], "year": "2009", "venue": "NASA Technical Reports Server", "doi": null, "url": "https://ntrs.nasa.gov/citations/20090039420", "abstract": "In 1963, during the ninth orbit of the Faith 7 capsule, astronaut Gordon Cooper skipped his nap and took some photos of the Earth below using a Hasselblad camera. The sole flier on the Mercury-Atlas 9 mission, Cooper took 24 photos - never-before-seen images including the Tibetan plateau, the crinkled heights of the Himalayas, and the jagged coast of Burma. From his lofty perch over 100 miles above the Earth, Cooper noted villages, roads, rivers, and even, on occasion, individual houses. In 1965, encouraged by the effectiveness of NASA s orbital photography experiments during the Mercury and subsequent Gemini manned space flight missions, U.S. Geological Survey (USGS) director William Pecora put forward a plan for a remote sensing satellite program that would collect information about the planet never before attainable. By 1972, NASA had built and launched Landsat 1, the first in a series of Landsat sensors that have combined to provide the longest continuous collection of space-based Earth imagery. The archived Landsat data - 37 years worth and counting - has provided a vast library of information allowing not only the extensive mapping of Earth s surface but also the study of its environmental changes, from receding glaciers and tropical deforestation to urban growth and crop harvests. Developed and launched by NASA with data collection operated at various times by the Agency, the National Oceanic and Atmospheric Administration (NOAA), Earth Observation Satellite Company (EOSAT, a private sector partnership that became Space Imaging Corporation in 1996), and USGS, Landsat sensors have recorded flooding from Hurricane Katrina, the building boom in Dubai, and the extinction of the Aral Sea, offering scientists invaluable insights into the natural and manmade changes that shape the world. Of the seven Landsat sensors launched since 1972, Landsat 5 and Landsat 7 are still operational. Though both are in use well beyond their intended lifespans, the mid-resolution satellites, which provide the benefit of images detailed enough to reveal large features like highways while still broad enough for global coverage, continue to scan the entirety of the Earth s surface. In 2012, NASA plans to launch the Landsat Data Continuity Mission (LDCM), or Landsat 8, to extend the Landsat program s contributions to cartography, water management, natural disaster relief planning, and more.", "grade": "B", "theme": "ch4_data_and_measurement", "source": "ntrs"}
{"key": "p2015", "title": "The NASA Earth Science Program and Small Satellites", "authors": ["Neeck, Steven P."], "year": "2015", "venue": "NASA Technical Reports Server", "doi": null, "url": "https://ntrs.nasa.gov/citations/20150022481", "abstract": "Earth's changing environment impacts every aspect of life on our planet and climate change has profound implications on society. Studying Earth as a single complex system is essential to understanding the causes and consequences of climate change and other global environmental concerns. NASA's Earth Science Division (ESD) shapes an interdisciplinary view of Earth, exploring interactions among the atmosphere, oceans, ice sheets, land surface interior, and life itself. This enables scientists to measure global and climate changes and to inform decisions by Government, other organizations, and people in the United States and around the world. The data collected and results generated are accessible to other agencies and organizations to improve the products and services they provide, including air quality indices, disaster prediction and response, agricultural yield projections, and aviation safety. ESD's Flight Program provides the spacebased observing systems and supporting infrastructure for mission operations and scientific data processing and distribution that support NASA's Earth science research and modeling activities. The Flight Program currently has 21 operating Earth observing space missions, including the recently launched Global Precipitation Measurement (GPM) mission, the Orbiting Carbon Observatory-2 (OCO-2), the Soil Moisture Active Passive (SMAP) mission, and the International Space Station (ISS) RapidSCAT and Cloud-Aerosol Transport System (CATS) instruments. The ESD has 22 more missions and instruments planned for launch over the next decade. These include first and second tier missions from the 2007 Earth Science Decadal Survey, Climate Continuity missions to assure availability of key climate data sets, and small-sized competitively selected orbital missions and instrument missions of opportunity belonging to the Earth Venture (EV) Program. Small satellites (~500 kg or less) are critical contributors to these current and future satellite missions. Some examples are the aforementioned Orbiting Carbon Observatory-2 (OCO-2), the Gravity Recovery and Climate Experiment Follow On (GRACE FO), and the Cyclone Global Navigation Satellite System (CYGNSS) microsatellite constellation. Small satellites also support ESD in space validation and risk reduction of enabling technologies (components and systems). The status of the ESD Flight Program and the role of small satellites will be discussed.", "grade": "B", "theme": "ch4_data_and_measurement", "source": "ntrs"}
{"key": "damadeo2020", "title": "The Stratospheric Aerosol and Gas Experiment (SAGE) IV Pathfinder", "authors": ["Robert Damadeo", "Charles Hill", "Michael Obland", "John Leckey"], "year": "2020", "venue": "NASA Technical Reports Server", "doi": null, "url": "https://ntrs.nasa.gov/citations/20205011684", "abstract": "Atmospheric aerosols and ozone are designated as observing system priorities in the 2017–2027 Decadal Survey report [1]. Accurate records of stratospheric aerosols are a vital piece of the puzzle regarding climate change. Stratospheric ozone has been the subject of observation and research for decades. Its importance is exhibited in the United States Clean Air Act [2], which mandates that NASA monitor atmospheric ozone. Measurements from satellites provided data on the initial decline of ozone in the late 1970s and early 1980s that supported the adoption of the Montreal Protocol, and current observations hint at a potential recovery. Adequate determination of that recovery requires continuous and, in the case of multiple instruments, overlapping data records. However, most current satellite systems are well beyond their expected lifetimes, and so we look towards the future of satellite observations of stratospheric ozone and aerosols to develop the Stratospheric Aerosol and Gas Experiment (SAGE) IV Pathfinder. Enabled by the NASA Earth Science Technology Office (ESTO)’s Instrument Incubator Program (IIP), the SAGE IV Pathfinder project has developed and validated a prototype demonstration that paves the way for a future SAGE IV spaceflight mission. Utilizing solar occultation imaging, SAGE IV will be capable of measuring ozone, aerosol, and other trace gas species with the same quality as previous SAGE instruments but with greatly improved pointing knowledge. Furthermore, current technological advancements allow SAGE IV to fit within a CubeSat framework and make use of commercial hardware, significantly reducing the size and cost when compared with traditional missions and enabling sustainability of future measurements. SAGE IV will meet the definition of the newly-recommended Venture-Continuity missions by “bringing forward innovative approaches to sustain measurements at lower costs”. The latest results from development of the SAGE IV Pathfinder are presented.\n\n[1] “Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space,” National Academies of Sciences, Engineering, and Medicine, 2018.\n[2] “United State Clean Air Act,” 42 U.S.C. 767 1b(d)(2).", "grade": "B", "theme": "ch4_data_and_measurement", "source": "ntrs"}
{"key": "martimort2023", "title": "On-Going and Planned Mission Concept Studies for the Preparation of Future ESA Earth Observation Satellites", "authors": ["P. Martimort", "B. C. Domínguez", "Arnaud Hélière", "Josep Roselló", "Martin Suess", "J. Angevain", "Adrien Bardou", "F. Bräuer"], "year": 2023, "venue": "IEEE International Geoscience and Remote Sensing Symposium", "doi": "10.1109/igarss52108.2023.10283393", "url": "https://doi.org/10.1109/igarss52108.2023.10283393", "abstract": "This paper will present the status of the on-going and planned mission concept studies in the period 2023 to 2025 in the frame of the ESA’s Future Earth Observation Programme (FutureEO).The European Space Agency (ESA) is conducting preparatory activities on innovative Earth Observation (EO) missions to foster better scientific understanding of the Earth system through research missions, respond to the requirements of the operational users via operational missions and assess the potential of \"Newspace\" approach with smallsat Earth Observation concepts to boost innovation through the Φsat missions.ESA’s program of EO research missions comprises Earth Explorers, Scouts and Mission of Opportunity. Earth Explorer missions objective is to advance Earth science by providing answers to key scientific questions on the Earth system. Up to date, five Earth Explorers have been launched and another five are in different stages of development. ESA’s Earth Explorer 11 mission candidates (CAIRT, Nitrosat, SEASTAR and WIVERN) are undergoing Phase 0 activities while preparatory activities to study mission concepts for the Earth Explorer 12 are expected to start in 2024.Missions of Opportunity are research missions implemented under cooperation frameworks with Space Agencies outside Europe and Canada. Next Generation Gravity Mission (NGGM) is a candidate Mission of Opportunity for ESA-NASA cooperation in the framework of MAGIC (MAss change and Geosciences International Constellation).Scouts are small budget research mission based on small satellites or CubeSats, implemented in three years and complementing Earth Explorers. Two mission concepts, TANGO and NanoMagSat, are currently undergoing risk retirement activities.Preparatory activities for operational mission are underway for the next generation of Sentinels in the frame of the Copernicus programme (e,g. Sentinel-2 Next Generation and Sentinel-3 Next Generation Optical, which are currently in phase 0) in close coordination with the European Commission). Preparatory activities are planned in the coming years for the next generation of meteorological missions (Meteosat 4th Generation and EPS/MetOp 3rd Generation) in close coordination with EUMETSAT.Φsat missions are CubeSat missions aimed to demonstrate radical and new technologies or remote sensing concepts in space, such as Φsat -2, which is currently under development and is focused on onboard Artificial Intelligence applications.", "grade": "A", "theme": "ch4_data_and_measurement", "source": "semanticscholar"}
{"key": "wulder2022", "title": "Fifty years of Landsat science and impacts", "authors": ["Michael A. Wulder", "David P. Roy", "Volker C. Radeloff", "Thomas R. Loveland", "Martha C. Anderson", "David M. Johnson", "Sean P. Healey", "Zhe Zhu"], "year": 2022, "venue": "Remote Sensing of Environment", "doi": "10.1016/j.rse.2022.113195", "url": "https://openalex.org/W4288420805", "abstract": "Since 1972, the Landsat program has been continually monitoring the Earth, to now provide 50 years of digital, multispectral, medium spatial resolution observations. Over this time, Landsat data were crucial for many scientific and technical advances. Prior to the Landsat program, detailed, synoptic depictions of the Earth's surface were rare, and the ability to acquire and work with large datasets was limited. The early years of the Landsat program delivered a series of technological breakthroughs, pioneering new methods, and demonstrating the ability and capacity of digital satellite imagery, creating a template for other global Earth observation missions and programs. Innovations driven by the Landsat program have paved the way for subsequent science, application, and policy support activities. The economic and scientific value of the knowledge gained through the Landsat program has been long recognized, and despite periods of funding uncertainty, has resulted in the program's 50 years of continuity, as well as substantive and ongoing improvements to payload and mission performance. Free and open access to Landsat data, enacted in 2008, was unprecedented for medium spatial resol", "grade": "A", "theme": "ch4_data_and_measurement", "source": "openalex"}
{"key": "zhu2019", "title": "Benefits of the free and open Landsat data policy", "authors": ["Zhe Zhu", "Michael A. Wulder", "David P. Roy", "Curtis E. Woodcock", "Matthew C. Hansen", "Volker C. Radeloff", "Sean P. Healey", "Crystal Schaaf"], "year": 2019, "venue": "Remote Sensing of Environment", "doi": "10.1016/j.rse.2019.02.016", "url": "https://openalex.org/W2916848715", "abstract": "The United States (U.S.) federal government provides imagery obtained by federally funded Earth Observation satellites typically at no cost. For many years Landsat was an exception to this trend, until 2008 when the United States Geological Survey (USGS) made Landsat data accessible via the internet for free. Substantial increases in downloads of Landsat imagery ensued and led to a rapid", "grade": "A", "theme": "ch4_data_and_measurement", "source": "openalex"}
{"key": "li2017", "title": "A Global Analysis of Sentinel-2A, Sentinel-2B and Landsat-8 Data Revisit Intervals and Implications for Terrestrial Monitoring", "authors": ["Jian Li", "David P. Roy"], "year": 2017, "venue": "Remote Sensing", "doi": "10.3390/rs9090902", "url": "https://openalex.org/W2751786729", "abstract": "Combination of different satellite data will provide increased opportunities for more frequent cloud-free surface observations due to variable cloud cover at the different satellite overpass times and dates. Satellite data from the polar-orbiting Landsat-8 (launched 2013), Sentinel-2A (launched 2015) and Sentinel-2B (launched 2017) sensors offer 10 m to 30 m multi-spectral global coverage. Together, they advance the virtual constellation paradigm for mid-resolution land imaging. In this study, a global analysis of Landsat-8, Sentinel-2A and Sentinel-2B metadata obtained from the committee on Earth Observation Satellite (CEOS) Visualization Environment (COVE) tool for 2016 is presented. A global equal area projection grid defined every 0.05° is used considering each sensor and combined together. Histograms, maps and global summary statistics of the temporal revisit intervals (minimum, mean, and maximum) and the number of observations are reported. The temporal observation frequency improvements afforded by sensor combination are shown to be significant. In particular, considering Landsat-8, Sentinel-2A, and Sentinel-2B together will provide a global median average revisit interval o", "grade": "A", "theme": "ch4_data_and_measurement", "source": "openalex"}
{"key": "phiri2017", "title": "Developments in Landsat Land Cover Classification Methods: A Review", "authors": ["Darius Phiri", "Justin Morgenroth"], "year": 2017, "venue": "Remote Sensing", "doi": "10.3390/rs9090967", "url": "https://openalex.org/W2755013453", "abstract": "Land cover classification of Landsat images is one of the most important applications developed from Earth observation satellites. The last four decades were marked by different developments in land cover classification methods of Landsat images. This paper reviews the developments in land cover classification methods for Landsat images from the 1970s to date and highlights key ways to optimize analysis of Landsat images in order to attain the desired results. This review suggests that the development of land cover classification methods grew alongside the launches of a new series of Landsat sensors and advancements in computer science. Most classification methods were initially developed in the 1970s and 1980s; however, many advancements in specific classifiers and algorithms have occurred in the last decade. The first methods of land cover classification to be applied to Landsat images were visual analyses in the early 1970s, followed by unsupervised and supervised pixel-based classification methods using maximum likelihood, K-means and Iterative Self-Organizing Data Analysis Technique (ISODAT) classifiers. After 1980, other methods such as sub-pixel, knowledge-based, contextual-", "grade": "A", "theme": "ch4_data_and_measurement", "source": "openalex"}
{"key": "masek2020", "title": "Landsat 9: Empowering Open Science and Applications Through Continuity", "authors": ["Jeffrey G. Masek", "Michael A. Wulder", "Brian Markham", "Joel Mccorkel", " Christopher J. Crawford", "James Storey", "Del T Jenstrom"], "year": "2020", "venue": "NASA Technical Reports Server", "doi": "10.1016/j.rse.2020.111968", "url": "https://ntrs.nasa.gov/citations/20210014057", "abstract": "The history of Earth observation from space is well reflected through the Landsat program. With data collection beginning with Landsat-1 in 1972, the program has evolved technical capabilities while maintaining continuity of land observations. In so doing, Landsat has provided a critical reference for assessing long-term changes to Earth's land environment due to both natural and human forcing. Poised for launch in mid-2021, the joint NASA-USGS Landsat 9 mission will continue this important data record. In many respects Landsat 9 is a clone of Landsat-8. The Operational Land Imager-2 (OLI-2) is largely identical to Landsat 8 OLI, providing calibrated imagery covering the solar reflected wavelengths. The Thermal Infrared Sensor-2 (TIRS-2) improves upon Landsat 8 TIRS, addressing known issues including stray light incursion and a malfunction of the instrument scene select mirror. In addition, Landsat 9 adds redundancy to TIRS-2, thus upgrading the instrument to a 5-year design life commensurate with other elements of the mission. Initial performance testing of OLI-2 and TIRS-2 indicate that the instruments are of excellent quality and expected to match or improve on Landsat 8 data quality. Landsat-9 will maintain the current data acquisition rate of up to 740 scenes per day, with these scenes available from the Landsat archive at no cost to users. In this communication, we provide background and rationale for the Landsat 9 mission, describe the instrument payloads and ground system, and discuss data products available from the Landsat 9 mission through USGS.", "grade": "B", "theme": "ch4_data_and_measurement", "source": "ntrs"}
{"key": "gj2023", "title": "PHILIPPINE EARTH OBSERVATION SATELLITE MISSIONS AND APPLICATIONS: A DECADAL SURVEY", "authors": ["Perez G.J."], "year": "2023", "venue": "International Archives of the Photogrammetry Remote Sensing and Spatial Information Sciences ISPRS Archives", "doi": "10.5194/isprs-archives-xlviii-1-w2-2023-1507-2023", "url": "https://doi.org/10.5194/isprs-archives-xlviii-1-w2-2023-1507-2023", "abstract": null, "grade": "A", "theme": "ch4_data_and_measurement", "source": "scopus"}
{"key": "jr1997", "title": "Satellite Systems Design/Simulation Environment: A Systems Approach to Pre-Phase A Design", "authors": ["Ferebee, Melvin J., Jr.", "Troutman, Patrick A.", "Monell, Donald W."], "year": "1997", "venue": "NASA Technical Reports Server", "doi": null, "url": "https://ntrs.nasa.gov/citations/20040105652", "abstract": "A toolset for the rapid development of small satellite systems has been created. The objective of this tool is to support the definition of spacecraft mission concepts to satisfy a given set of mission and instrument requirements. The objective of this report is to provide an introduction to understanding and using the SMALLSAT Model. SMALLSAT is a computer-aided Phase A design and technology evaluation tool for small satellites. SMALLSAT enables satellite designers, mission planners, and technology program managers to observe the likely consequences of their decisions in terms of satellite configuration, non-recurring and recurring cost, and mission life cycle costs and availability statistics. It was developed by Princeton Synergetic, Inc. and User Systems, Inc. as a revision of the previous TECHSAT Phase A design tool, which modeled medium-sized Earth observation satellites. Both TECHSAT and SMALLSAT were developed for NASA.", "grade": "B", "theme": "ch4_data_and_measurement", "source": "ntrs"}
{"key": "c1986", "title": "Monitored background radiometer", "authors": ["Ruel, C.", "Larouche, M.", "Donato, M."], "year": "1986", "venue": "NASA Technical Reports Server", "doi": null, "url": "https://ntrs.nasa.gov/citations/19880001449", "abstract": "The infrared (IR) testing of the Olympus thermal model has provided a capability to perform cost effective thermal balance testing of satellites and satellite components. A high-accuracy monitored background radiometer was developed for the measurement of absorbed radiation heat flux encountered during IR thermal vacuum testing of spacecraft. The design, development, and calibration of this radiometer is described.", "grade": "B", "theme": "ch4_data_and_measurement", "source": "ntrs"}
{"key": "jim2012", "title": "Progress Towards a 2012 Landsat Launch", "authors": ["Irons, Jim", "Sabelhaus, Phil", "Masek, Jeff", "Cook, Bruce", "Dabney, Phil", "Loveland, Tom"], "year": "2012", "venue": "NASA Technical Reports Server", "doi": null, "url": "https://ntrs.nasa.gov/citations/20120009180", "abstract": "The Landsat Data Continuity Mission (LDCM) is on schedule for a December 2012 launch date. The mission is being managed by an interagency partnership between NASA and the U.S. Geological Survey (USGS). NASA leads the development and launch of the satellite observatory while leads ground system development. USGS will assume responsibility for operating the satellite and for collecting, archiving, and distributing the LDCM data following launch. When launched the satellite will carry two sensors into orbit. The Operational Land Imager (OLI) will collect data for nine shortwave spectral bands with a spatial resolution of 30 m (with a 15 m panchromatic band). The Thermal Infrared Sensor (TIRS) will coincidently collect data for two thermal infrared bands with a spatial resolution of 100 m. The OLI is fully assembled and tested and has been shipped by it?s manufacturer, Ball Aerospace and Technology Corporation, to the Orbital Sciences Corporation (Orbital) facility where it is being integrated onto the LDCM spacecraft. Pre-launch testing indicates that OLI will meet all performance specification with margin. TIRS is in development at the NASA Goddard Space Flight Center (GSFC) and is in final testing before shipping to the Orbital facility in January, 2012. The ground data processing system is in development at the USGS Earth Resources Observation and Science (EROS) Center. The presentation will describe the LDCM satellite system, provide the status of system development, and present prelaunch performance data for OLI and TIRS. The USGS has committed to renaming the satellite as Landsat 8 following launch.", "grade": "B", "theme": "ch4_data_and_measurement", "source": "ntrs"}
{"key": "miner2024", "title": "A Decadal Survey Without Analogs: Earth Observation Needs for a Warming World", "authors": ["K. R. Miner", "R. K. Braghiere", "C. E. Miller", "N. Schlegel", "D. Schimel"], "year": 2024, "venue": "AGU Advances", "doi": "10.1029/2023av001148", "url": "https://doi.org/10.1029/2023av001148", "abstract": "<jats:title>Abstract</jats:title><jats:p>Since 2007, the National Academy for Sciences Engineering and Medicine (NASEM) has recommended Earth Science research and investment priorities every 10 years. The Decadal Survey balances the continuation of essential climate variable time series against unmet measurement needs and new Earth Observations made possible by technological breakthroughs. The next survey (2027–2028, DS28) will be framed by a rapidly changing world, and it will be critical to anticipate the observational needs of the 2030s–2040s, a world increasingly dominated by climate extremes and a rapidly changing Earth system. Here, we highlight some of the changes that factor into a framework for the DS28.</jats:p>", "grade": "A", "theme": "ch4_data_and_measurement", "source": "crossref"}
{"key": "mccabe2017", "title": "The future of Earth observation in hydrology", "authors": ["Matthew F. McCabe", "Matthew Rodell", "Douglas Alsdorf", "Diego G. Miralles", "R. Uijlenhoet", "Wolfgang Wagner", "Arko Lucieer", "Rasmus Houborg"], "year": 2017, "venue": "Hydrology and earth system sciences", "doi": "10.5194/hess-21-3879-2017", "url": "https://openalex.org/W2587446396", "abstract": "In just the past five years, the field of Earth observation has progressed beyond the offerings of conventional space agency based platforms to include a plethora of sensing opportunities afforded by CubeSats, Unmanned Aerial Vehicles (UAVs), and smartphone technologies that are being embraced by both for-profit companies and individual researchers. Over the previous decades, space agency efforts have brought forth well-known and immensely useful satellites such as the Landsat series and the Gravity Research and Climate Experiment (GRACE) system, with costs typically on the order of one billion dollars per satellite and with concept-to-launch timelines on the order of two decades (for new missions). More recently, the proliferation of smartphones has helped to miniaturise sensors and energy requirements, facilitating advances in the use of CubeSats that can be launched by the dozens, while providing ultra-high (3-5 m) resolution sensing of the Earth on a daily basis. Start-up companies that did not exist five years ago now operate more satellites in orbit than any space agency, and at costs that are a mere fraction of the cost of traditional satellite missions. With these advances ", "grade": "A", "theme": "ch4_data_and_measurement", "source": "openalex"}
{"key": "qian2021", "title": "Hyperspectral Satellites, Evolution, and Development History", "authors": ["Shen‐En Qian"], "year": 2021, "venue": "IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing", "doi": "10.1109/jstars.2021.3090256", "url": "https://openalex.org/W3174056964", "abstract": "Hyperspectral imaging has been emerged as a new generation of technology for earth observation and space exploration since the beginning of this millennium and widely used in various disciplinary and applications. The fascinating detailed spectral information acquired by hyperspectral imagers often yields results not possible with multispectral or other types of satellites. This article provides an overview of spaceborne hyperspectral imagers, technology evolution, and development history. After introduction of hyperspectral satellites, it first describes the principle of hyperspectral imaging. It then reviews the history of hyperspectral technology development, starting from the first airborne hyperspectral imager AIS built in early 1980s, the first operational airborne hyperspectral imager AVIRIS developed since middle 1980s, the first commercial airborne hyperspectral instrument CASI fabricated since late 1980s, followed by the development of hyperspectral technology in Canada between 1980s and 1990s, and the NASA planned orbiting hyperspectral imagers in 1990s, until the first spaceborne hyperspectral imager Hyperion launched in 2000. This article summarizes the survey carried ", "grade": "A", "theme": "ch4_data_and_measurement", "source": "openalex"}
{"key": "andersen2012", "title": "Competing risks in epidemiology: possibilities and pitfalls", "authors": ["P. K. Andersen", "R. B. Geskus", "T. de Witte", "H. Putter"], "year": 2012, "venue": "International Journal of Epidemiology", "doi": "10.1093/ije/dyr213", "url": "https://doi.org/10.1093/ije/dyr213", "abstract": "BACKGROUND: In studies of all-cause mortality, the fundamental epidemiological concepts of rate and risk are connected through a well-defined one-to-one relation. An important consequence of this relation is that regression models such as the proportional hazards model that are defined through the hazard (the rate) immediately dictate how the covariates relate to the survival function (the risk). METHODS: This introductory paper reviews the concepts of rate and risk and their one-to-one relation in all-cause mortality studies and introduces the analogous concepts of rate and risk in the context of competing risks, the cause-specific hazard and the cause-specific cumulative incidence function. RESULTS: The key feature of competing risks is that the one-to-one correspondence between cause-specific hazard and cumulative incidence, between rate and risk, is lost. This fact has two important implications. First, the naïve Kaplan-Meier that takes the competing events as censored observations, is biased. Secondly, the way in which covariates are associated with the cause-specific hazards may not coincide with the way these covariates are associated with the cumulative incidence. An exampl", "grade": "A", "theme": "ch5_research_design", "source": "seed"}
{"key": "santanna2020", "title": "Doubly robust difference-in-differences estimators", "authors": ["P. H. C. Sant'Anna", "J. Zhao"], "year": 2020, "venue": "Journal of Econometrics", "doi": "10.1016/j.jeconom.2020.06.003", "url": "https://doi.org/10.1016/j.jeconom.2020.06.003", "abstract": null, "grade": "A", "theme": "ch5_research_design", "source": "seed"}
{"key": "zhang2017", "title": "Survival analysis in the presence of competing risks", "authors": ["Zhongheng Zhang"], "year": 2017, "venue": "Annals of Translational Medicine", "doi": "10.21037/atm.2016.08.62", "url": "https://openalex.org/W2531618711", "abstract": "Survival analysis in the presence of competing risks imposes additional challenges for clinical investigators in that hazard function (the rate) has no one-to-one link to the cumulative incidence function (CIF, the risk). CIF is of particular interest and can be estimated non-parametrically with the use cuminc() function. This function also allows for group comparison and visualization of estimated CIF. The effect of covariates on cause-specific hazard can be explored using conventional Cox proportional hazard model by treating competing events as censoring. However, the effect on hazard cannot be directly linked to the effect on CIF because there is no one-to-one correspondence between hazard and cumulative incidence. Fine-Gray model directly models the covariate effect on CIF and it reports subdistribution hazard ratio (SHR). However, SHR only provide information on the ordering of CIF curves at different levels of covariates, it has no practical interpretation as HR in the absence of competing risks. Fine-Gray model can be fit with crr() function shipped with the cmprsk package. Time-varying covariates are allowed in the crr() function, which is specified by cov2 and tf argument", "grade": "A", "theme": "ch5_research_design", "source": "openalex"}
{"key": "zaino2025", "title": "Overestimation of Cardiovascular Mortality Risk by Kaplan-Meier in Competing Risks Settings: A Web-Based Calculator and NHANES Analysis", "authors": ["Mohammad Zaino"], "year": 2025, "venue": "International Journal of Statistics in Medical Research", "doi": "10.6000/1929-6029.2025.14.31", "url": "https://doi.org/10.6000/1929-6029.2025.14.31", "abstract": "Background: Traditional Kaplan-Meier (KM) event rates are widely used for cardiovascular risk prediction and tend to overestimate absolute event risk for patients by censoring competing events, such as non-cardiovascular death. Competing risks analysis (CRA), which account for such terminal events, offers more accurate estimates. However, its application in a web-based health analytics remains limited. \nMethods: Using a simulated cohort (n = 2,500; 100 repetitions) and the 1999–2000 NHANES cohort (n = 2,480) with 2019 National Death Index mortality linkage, the researcher compared KM estimates to CRA’s Cumulative Incidence Function (CIF), implemented via Aalen-Johansen estimators and Fine-Gray subdistribution hazard models. We assessed relative differences (bias) in 5-, 10-, 15-, and 20-year cardiovascular mortality predictions across risk strata. Findings informed a web-based calculator prototype that dynamically estimates age-specific KM and CIF probabilities while highlighting potential misclassification risks. \nResults: KM consistently overestimated cardiovascular mortality risk compared to CIF. In the NHANES cohort, KM estimated the 5-year risk to be 5.85% higher than the actual rate (4.37% vs. 4.13%) and 20-year risk by 28.3% (20.02% vs. 15.60%). In the simulated data, KM overestimated the 5-year risk by 7.63% (5.84% vs. 5.42%) and the 20-year risk by 31.17% (21.37% vs. 16.25%). KM-based models tend to misclassify a substantial portion of patients into higher-risk groups compared to CIF-adjusted models. \nConclusion: This study demonstrates that Kaplan-Meier consistently overestimates cardiovascular mortality in comparison to competing risk methods across five time points, through using both simulated and nationally representative data. We quantify this overestimation and provide an online calculator that shows differences by age. Our tool improves the usability and interpretability of competing risks analysis for older adults in digital health settings, in contrast to tools like SCORE2.", "grade": "A", "theme": "ch5_research_design", "source": "semanticscholar"}
{"key": "wolbers2009", "title": "Prognostic Models With Competing Risks", "authors": ["Marcel Wolbers", "Michael Koller", "Jacqueline C.M. Witteman", "Ewout W. Steyerberg"], "year": 2009, "venue": "Epidemiology", "doi": "10.1097/ede.0b013e3181a39056", "url": "https://openalex.org/W1992557526", "abstract": "Clinical decision-making often relies on a subject's absolute risk of a disease event of interest. However, in a frail population, competing risk events may preclude the occurrence of the event of interest. We review competing-risk regression models with a view toward predictive modeling. We show how measures of prognostic performance (such as calibration and discrimination) can be adapted to the competing-risks setting. An example of coronary heart disease (CHD) prediction in women aged 55-90 years in the Rotterdam study is used to illustrate the proposed methods, and to compare the Fine and Gray regression model to 2 alternative approaches: (1) a standard Cox survival model, which ignores the competing risk of non-CHD death, and (2) a cause-specific hazards model, which combines proportional hazards models for the event of interest and the competing event. The Fine and Gray model and the cause-specific hazards model perform similarly. However, the standard Cox model substantially overestimates 10-year risk of CHD; it classifies 18% of the individuals as high risk (>20%), compared with only 8% according to the Fine and Gray model. We conclude that competing risks have to be consid", "grade": "A", "theme": "ch5_research_design", "source": "openalex"}
{"key": "wu2025", "title": "Analysis of Competing Risks Data with Covariates Subject to Detection Limits", "authors": ["Yilin Wu", "Rui Huang", "Huixia Judy Wang", "Liming Xiang"], "year": 2025, "venue": "Journal of Computational And Graphical Statistics", "doi": "10.1080/10618600.2025.2526420", "url": "https://doi.org/10.1080/10618600.2025.2526420", "abstract": "Abstract Competing risks data are commonly encountered in biomedical studies when subjects may experience multiple types of events and the occurrence of the primary event of interest can be precluded by a competing event. Challenges arise for regression analysis of such data with covariates subject to censoring due to detection limits. We propose a novel multiple imputation method for inference under Fine-Gray’s subdistribution hazard model with censored covariates subject to detection limits. Our proposal uses the information from the fully observed covariate values and the failure outcomes to impute the censored covariates iteratively using rejection sampling, which makes the imputation model compatible to the substantive model and the estimation efficiency improve significantly. We show the consistency and asymptotic normality of the resulting estimator and demonstrate its promising finite sample performance through simulation studies. Moreover, we extend this new proposal to assess the impacts of censored covariates on the predictive performance of the competing risks model. To illustrate its practical utility, we provide an application to the data from a study of community acquired pneumonia. Supplementary materials for this article are available online.", "grade": "A", "theme": "ch5_research_design", "source": "semanticscholar"}
{"key": "zhang2011", "title": "A proportional hazards regression model for the subdistribution with right‐censored and left‐truncated competing risks data", "authors": ["Xu Zhang", "Mei‐Jie Zhang", "Jason P. Fine"], "year": 2011, "venue": "Statistics in Medicine", "doi": "10.1002/sim.4264", "url": "https://openalex.org/W2134207259", "abstract": "With competing risks failure time data, one often needs to assess the covariate effects on the cumulative incidence probabilities. Fine and Gray proposed a proportional hazards regression model to directly model the subdistribution of a competing risk. They developed the estimating procedure for right-censored competing risks data, based on the inverse probability of censoring weighting. Right-censored and left-truncated competing risks data sometimes occur in biomedical researches. In this paper, we study the proportional hazards regression model for the subdistribution of a competing risk with right-censored and left-truncated data. We adopt a new weighting technique to estimate the parameters in this model. We have derived the large sample properties of the proposed estimators. To illustrate the application of the new method, we analyze the failure time data for children with acute leukemia. In this example, the failure times for children who had bone marrow transplants were left truncated.", "grade": "A", "theme": "ch5_research_design", "source": "openalex"}
{"key": "ahiagadagbui2014b", "title": "Rethinking construction cost overruns: cognition, learning and estimation", "authors": ["Dominic D. Ahiaga-Dagbui", "Simon Smith"], "year": 2014, "venue": "Journal of Financial Management of Property and Construction", "doi": "10.1108/jfmpc-06-2013-0027", "url": "https://openalex.org/W2091515513", "abstract": "Purpose – Drawing on mainstream arguments in the literature, the paper presents a coherent and holistic view on the causes of cost overruns, and the dynamics between cognitive dispositions, learning and estimation. A cost prediction model has also been developed using data mining for estimating final cost of projects. The paper aims to discuss these issues. Design/methodology/approach – A mixed-method approach was adopted: a qualitative exploration of the causes of cost overrun followed by an empirical development of a final cost model using artificial neural networks. Findings – A conceptual model to distinguish between the often conflated causes of underestimation and cost overruns on large publicly funded projects. The empirical model developed in this paper achieved an average absolute percentage error of 3.67 percent with 87 percent of the model predictions within a range of ±5 percent of the actual final cost. Practical implications – The model developed can be converted to a desktop package for quick cost predictions and the generation of various alternative solutions for a construction project in a sort of what-if analysis for the purposes of comparison. The use of the mode", "grade": "A", "theme": "ch5_research_design", "source": "openalex"}
{"key": "bellego2023", "title": "The chained difference-in-differences", "authors": ["Christophe Bell'ego", "David Benatia", "Vincent Dortet-Bernardet"], "year": 2023, "venue": "Journal of Econometrics", "doi": "10.1016/j.jeconom.2024.105783", "url": "https://doi.org/10.1016/j.jeconom.2024.105783", "abstract": "This paper studies the identification, estimation, and inference of long-term (binary) treatment effect parameters when balanced panel data is not available, or consists of only a subset of the available data. We develop a new estimator: the chained difference-in-differences, which leverages the overlapping structure of many unbalanced panel data sets. This approach consists in aggregating a collection of short-term treatment effects estimated on multiple incomplete panels. Our estimator accommodates (1) multiple time periods, (2) variation in treatment timing, (3) treatment effect heterogeneity, (4) general missing data patterns, and (5) sample selection on observables. We establish the asymptotic properties of the proposed estimator and discuss identification and efficiency gains in comparison to existing methods. Finally, we illustrate its relevance through (i) numerical simulations, and (ii) an application about the effects of an innovation policy in France.", "grade": "A", "theme": "ch5_research_design", "source": "semanticscholar"}
{"key": "austin2017", "title": "Practical recommendations for reporting Fine-Gray model analyses for competing risk data", "authors": ["P. C. Austin", "J. P. Fine"], "year": 2017, "venue": "Statistics in Medicine", "doi": "10.1002/sim.7501", "url": "https://doi.org/10.1002/sim.7501", "abstract": "In survival analysis, a competing risk is an event whose occurrence precludes the occurrence of the primary event of interest. Outcomes in medical research are frequently subject to competing risks. In survival analysis, there are 2 key questions that can be addressed using competing risk regression models: first, which covariates affect the rate at which events occur, and second, which covariates affect the probability of an event occurring over time. The cause‐specific hazard model estimates the effect of covariates on the rate at which events occur in subjects who are currently event‐free. Subdistribution hazard ratios obtained from the Fine‐Gray model describe the relative effect of covariates on the subdistribution hazard function. Hence, the covariates in this model can also be interpreted as having an effect on the cumulative incidence function or on the probability of events occurring over time. We conducted a review of the use and interpretation of the Fine‐Gray subdistribution hazard model in articles published in the medical literature in 2015. We found that many authors provided an unclear or incorrect interpretation of the regression coefficients associated with this m", "grade": "A", "theme": "ch6_analysis_plan", "source": "seed"}
{"key": "coviello2004", "title": "Cumulative Incidence Estimation in the Presence of Competing Risks", "authors": ["V. Coviello", "M. Boggess"], "year": 2004, "venue": "The Stata Journal", "doi": "10.1177/1536867x0400400201", "url": "https://doi.org/10.1177/1536867x0400400201", "abstract": "When competing risks are present, the appropriate estimate of the failure probabilities is the cumulative incidence. stcompet creates new variables containing the estimate of this function, its standard error, and ln(– ln) transformed confidence bounds. Two examples are presented to illustrate the use of the new command and some key features of the cumulative incidence.", "grade": "B", "theme": "ch6_analysis_plan", "source": "seed"}
{"key": "geskus2010", "title": "Cause-Specific Cumulative Incidence Estimation and the Fine and Gray Model Under Both Left Truncation and Right Censoring", "authors": ["Ronald B. Geskus"], "year": 2010, "venue": "Biometrics", "doi": "10.1111/j.1541-0420.2010.01420.x", "url": "https://openalex.org/W2108513094", "abstract": "Summary The standard estimator for the cause-specific cumulative incidence function in a competing risks setting with left truncated and/or right censored data can be written in two alternative forms. One is a weighted empirical cumulative distribution function and the other a product-limit estimator. This equivalence suggests an alternative view of the analysis of time-to-event data with left truncation and right censoring: individuals who are still at risk or experienced an earlier competing event receive weights from the censoring and truncation mechanisms. As a consequence, inference on the cumulative scale can be performed using weighted versions of standard procedures. This holds for estimation of the cause-specific cumulative incidence function as well as for estimation of the regression parameters in the Fine and Gray proportional subdistribution hazards model. We show that, with the appropriate filtration, a martingale property holds that allows deriving asymptotic results for the proportional subdistribution hazards model in the same way as for the standard Cox proportional hazards model. Estimation of the cause-specific cumulative incidence function and regression on the", "grade": "A", "theme": "ch6_analysis_plan", "source": "openalex"}
{"key": "barley2010", "title": "Heritage and Advanced Technology Systems Engineering Lessons Learned from NASA Deep Space Missions", "authors": ["Bryan Barley", "Allen S. Bacskay", "Marilyn Newhouse"], "year": 2010, "venue": null, "doi": "10.2514/6.2010-8622", "url": "https://openalex.org/W2169376459", "abstract": "In the design and development of complex spacecraft missions, project teams frequently assume the use of advanced technology systems or heritage systems to enable a mission or reduce the overall mission risk and cost. As projects proceed through the development life cycle, increasingly detailed knowledge of the advanced and heritage systems within the spacecraft and mission environment identifies unanticipated technical issues. Resolving these issues often results in cost overruns and schedule impacts. The National Aeronautics and Space Administration (NASA) Discovery &amp; New Frontiers (D&amp;NF) Program Office at Marshall Space Flight Center (MSFC) recently studied cost overruns and schedule delays for 5 missions. The goal was to identify the underlying causes for the overruns and delays, and to develop practical mitigations to assist the D&amp;NF projects in identifying potential risks and controlling the associated impacts to proposed mission costs and schedules. The study found that optimistic hardware/software inheritance and technology readiness assumptions caused cost and schedule growth for four of the five missions studied. The cost and schedule growth was not found to r", "grade": "B", "theme": "ch6_analysis_plan", "source": "openalex"}
{"key": "tai2018", "title": "Estimating sample size in the presence of competing risks – Cause-specific hazard or cumulative incidence approach?", "authors": ["BC Tai", "ZJ Chen", "D Machin"], "year": 2018, "venue": "Statistical Methods in Medical Research", "doi": "10.1177/0962280215623107", "url": "https://doi.org/10.1177/0962280215623107", "abstract": "<jats:p>\n                    In designing randomised clinical trials involving competing risks endpoints, it is important to consider competing events to ensure appropriate determination of sample size. We conduct a simulation study to compare sample sizes obtained from the cause-specific hazard and cumulative incidence (CMI) approaches, by first assuming exponential event times. As the proportional subdistribution hazard assumption does not hold for the CMI exponential (CMI\n                    <jats:sub>Exponential</jats:sub>\n                    ) model, we further investigate the impact of violation of such an assumption by comparing the results obtained from the CMI exponential model with those of a CMI model assuming a Gompertz distribution (CMI\n                    <jats:sub>Gompertz</jats:sub>\n                    ) where the proportional assumption is tenable. The simulation suggests that the CMI\n                    <jats:sub>Exponential</jats:sub>\n                    approach requires a considerably larger sample size when treatment reduces the hazards of both the main event, A, and the competing risk, B. When treatment has a beneficial effect on A but no effect on B, the sample sizes required by both methods are largely similar, especially for large reduction in the main risk. If treatment has a protective effect on A but adversely affects B, then the sample size required by CMI\n                    <jats:sub>Exponential</jats:sub>\n                    is notably smaller than cause-specific hazard for small to moderate reduction in the main risk. Further, a smaller sample size is required for CMI\n                    <jats:sub>Gompertz</jats:sub>\n                    as compared with CMI\n                    <jats:sub>Exponential</jats:sub>\n                    . The choice between a cause-specific hazard or CMI model in competing risks outcomes has implications on the study design. This should be made on the basis of the clinical question of interest and the validity of the associated model assumption.\n                  </jats:p>", "grade": "A", "theme": "ch6_analysis_plan", "source": "crossref"}
{"key": "liu2018", "title": "Optimism Bias Evaluation and Decision-Making Risk Forecast on Bridge Project Cost Based on Reference Class Forecasting: Evidence from China", "authors": ["Huimin Liu", "Canhui Jiang", "Yan Liu", "Marcel Hertogh", "Xue Lyu"], "year": 2018, "venue": "Sustainability", "doi": "10.3390/su10113981", "url": "https://doi.org/10.3390/su10113981", "abstract": "<jats:p>The high uncertainty of megaproject results in increasing complexity in the decision-making and ultimately leads to different degrees of cost overrun and project delays. One of the critical reasons for cost overrun and delay is the optimism bias of decision makers. Although the previous literature has analyzed the cost overrun distribution of bridges, roads and other infrastructure projects, there is still a lack of research on how to make more reasonable decisions according to the cost overrun risk and cost-benefit theory by considering the expectation of cost overrun. Therefore, this paper firstly measures optimism bias by conducting the field research and interviews regarding over 30 long bridges in China. On the basis of the optimism bias measure, a decision-making risk model of bridge projects with the expectation of cost overrun has been built. Then the paper takes Hangzhou Bay Bridge as an example to discuss the influence of cost overrun predication, implicit benefits and the project’s operation time on NPV results. Moreover, the probability of project unbuildability risk under different degrees of cost optimism bias has also been discussed. Finally, suggestions for risk forecast are provided for decision-makers to make more objective and comprehensive judgments.</jats:p>", "grade": "A", "theme": "ch6_analysis_plan", "source": "crossref"}
{"key": "beyersmann2008", "title": "Time-dependent covariates in the proportional subdistribution hazards model for competing risks", "authors": ["Jan Beyersmann", "Martin Schumacher"], "year": 2008, "venue": "Biostatistics", "doi": "10.1093/biostatistics/kxn009", "url": "https://openalex.org/W2104487175", "abstract": "Separate Cox analyses of all cause-specific hazards are the standard technique of choice to study the effect of a covariate in competing risks, but a synopsis of these results in terms of cumulative event probabilities is challenging. This difficulty has led to the development of the proportional subdistribution hazards model. If the covariate is known at baseline, the model allows for a summarizing assessment in terms of the cumulative incidence function. black Mathematically, the model also allows for including random time-dependent covariates, but practical implementation has remained unclear due to a certain risk set peculiarity. We use the intimate relationship of discrete covariates and multistate models to naturally treat time-dependent covariates within the subdistribution hazards framework. The methodology then straightforwardly translates to real-valued time-dependent covariates. As with classical survival analysis, including time-dependent covariates does not result in a model for probability functions anymore. Nevertheless, the proposed methodology provides a useful synthesis of separate cause-specific hazards analyses. We illustrate this with hospital infection data, w", "grade": "A", "theme": "ch6_analysis_plan", "source": "openalex"}
{"key": "austin2017b", "title": "The number of primary events per variable affects estimation of the subdistribution hazard competing risks model.", "authors": ["P. Austin", "A. Allignol", "J. Fine"], "year": 2017, "venue": "Journal of Clinical Epidemiology", "doi": "10.1016/j.jclinepi.2016.11.017", "url": "https://doi.org/10.1016/j.jclinepi.2016.11.017", "abstract": "OBJECTIVES\nTo examine the effect of the number of events per variable (EPV) on the accuracy of estimated regression coefficients, standard errors, empirical coverage rates of estimated confidence intervals, and empirical estimates of statistical power when using the Fine-Gray subdistribution hazard regression model to assess the effect of covariates on the incidence of events that occur over time in the presence of competing risks.\n\n\nSTUDY DESIGN AND SETTING\nMonte Carlo simulations were used. We considered two different definitions of the number of EPV. One included events of any type that occurred (both primary events and competing events), whereas the other included only the number of primary events that occurred.\n\n\nRESULTS\nThe definition of EPV that included only the number of primary events was preferable to the alternative definition, as the number of competing events had minimal impact on estimation. In general, 40-50 EPV were necessary to ensure accurate estimation of regression coefficients and associated quantities. However, if all of the covariates are continuous or are binary with moderate prevalence, then 10 EPV are sufficient to ensure accurate estimation.\n\n\nCONCLUSION\nAnalysts must base the number of EPV on the number of primary events that occurred.", "grade": "A", "theme": "ch6_analysis_plan", "source": "semanticscholar"}
{"key": "mozumder2017", "title": "stpm2cr: A flexible parametric competing risks model using a direct likelihood approach for the cause-specific cumulative incidence function", "authors": ["S. I. Mozumder", "M. Rutherford", "P. Lambert"], "year": 2017, "venue": "The Stata Journal", "doi": "10.1177/1536867x1701700212", "url": "https://doi.org/10.1177/1536867x1701700212", "abstract": "In competing-risks analysis, the cause-specific cumulative incidence function (CIF) is usually obtained in a modeling framework by either 1) transforming on all cause-specific hazards or 2) transforming by using a direct relationship with the subdistribution hazard function. We expand on current competing-risks methodology from within the flexible parametric survival modeling framework and focus on the second approach. This approach models all cause-specific CIFs simultaneously and is more useful for answering prognostic-related questions. We propose the direct flexible parametric survival modeling approach for the cause-specific CIF. This approach models the (log cumulative) baseline hazard without requiring numerical integration, which leads to benefits in computational time. It is also easy to make out-of-sample predictions to estimate more useful measures and incorporate alternative link functions, for example, logit links. To implement these methods, we introduce a new estimation command, stpm2cr, and demonstrate useful predictions from the model through an illustrative melanoma dataset.", "grade": "A", "theme": "ch6_analysis_plan", "source": "semanticscholar"}
{"key": "austin2019", "title": "A review of the use of time‐varying covariates in the Fine‐Gray subdistribution hazard competing risk regression model", "authors": ["Peter C. Austin", "Aurélien Latouche", "Jason P. Fine"], "year": 2019, "venue": "Statistics in Medicine", "doi": "10.1002/sim.8399", "url": "https://openalex.org/W2982693598", "abstract": "In survival analysis, time-varying covariates are covariates whose value can change during follow-up. Outcomes in medical research are frequently subject to competing risks (events precluding the occurrence of the primary outcome). We review the types of time-varying covariates and highlight the effect of their inclusion in the subdistribution hazard model. External time-dependent covariates are external to the subject, can effect the failure process, but are not otherwise involved in the failure mechanism. Internal time-varying covariates are measured on the subject, can effect the failure process directly, and may also be impacted by the failure mechanism. In the absence of competing risks, a consequence of including internal time-dependent covariates in the Cox model is that one cannot estimate the survival function or the effect of covariates on the survival function. In the presence of competing risks, the inclusion of internal time-varying covariates in a subdistribution hazard model results in the loss of the ability to estimate the cumulative incidence function (CIF) or the effect of covariates on the CIF. Furthermore, the definition of the risk set for the subdistribution ", "grade": "A", "theme": "ch6_analysis_plan", "source": "openalex"}
{"key": "bakoyannis2017", "title": "Semiparametric regression on cumulative incidence function with interval-censored competing risks data", "authors": ["G. Bakoyannis", "Menggang Yu", "C. Yiannoutsos"], "year": 2017, "venue": "Statistics in Medicine", "doi": "10.1002/sim.7350", "url": "https://doi.org/10.1002/sim.7350", "abstract": "Many biomedical and clinical studies with time‐to‐event outcomes involve competing risks data. These data are frequently subject to interval censoring. This means that the failure time is not precisely observed but is only known to lie between two observation times such as clinical visits in a cohort study. Not taking into account the interval censoring may result in biased estimation of the cause‐specific cumulative incidence function, an important quantity in the competing risks framework, used for evaluating interventions in populations, for studying the prognosis of various diseases, and for prediction and implementation science purposes. In this work, we consider the class of semiparametric generalized odds rate transformation models in the context of sieve maximum likelihood estimation based on B‐splines. This large class of models includes both the proportional odds and the proportional subdistribution hazard models (i.e., the Fine–Gray model) as special cases. The estimator for the regression parameter is shown to be consistent, asymptotically normal and semiparametrically efficient. Simulation studies suggest that the method performs well even with small sample sizes. As an illustration, we use the proposed method to analyze data from HIV‐infected individuals obtained from a large cohort study in sub‐Saharan Africa. We also provide the R function ciregic that implements the proposed method and present an illustrative example. Copyright © 2017 John Wiley & Sons, Ltd.", "grade": "A", "theme": "ch6_analysis_plan", "source": "semanticscholar"}
{"key": "carvalho2026", "title": "FORECASTING AND FINANCIAL PREDICTABILITY IN COMPLEX INFRASTRUCTURE AND ENERGY PROJECTS", "authors": ["Eduardo Monterisi Almeida de Carvalho"], "year": 2026, "venue": "Revista de Estudos Interdisciplinares", "doi": "10.23900/artefactum.v25i2.2931", "url": "https://doi.org/10.23900/artefactum.v25i2.2931", "abstract": "Complex infrastructure and energy projects are highly exposed to cost overruns, delays, contractual changes, macroeconomic variations, and scope revisions. In this context, this article analyzes how financial forecasting can enhance economic predictability and improve executive decision-making in capital-intensive projects. The research is qualitative and theoretical-analytical in nature, developed through a narrative literature review. The analysis articulates contributions on cost overrun, optimism bias, strategic misrepresentation, reference class forecasting, project controls, and the finance function. The findings indicate that forecasting should not be treated as a simple spreadsheet update or reporting routine, but as a mechanism for continuously revising the assumptions that support the project’s economic trajectory. When integrated with risk analysis, estimate at completion, contingency management, and comparison with historical reference classes, financial forecasting strengthens the ability to anticipate deviations, revise scenarios, and support decisions regarding contracts, cash flow, schedule, margin, and economic viability. The article concludes that financial predictability in complex projects does not depend on eliminating uncertainty, but on the institutional capacity to recognize, measure, and translate it into decision-oriented information.", "grade": "A", "theme": "ch6_analysis_plan", "source": "semanticscholar"}
{"key": "zhou2011", "title": "Competing risks regression for clustered data", "authors": ["Bo Zhou", "Jason P. Fine", "Aurélien Latouche", "Myriam Labopin"], "year": 2011, "venue": "Biostatistics", "doi": "10.1093/biostatistics/kxr032", "url": "https://openalex.org/W2127244250", "abstract": "A population average regression model is proposed to assess the marginal effects of covariates on the cumulative incidence function when there is dependence across individuals within a cluster in the competing risks setting. This method extends the Fine-Gray proportional hazards model for the subdistribution to situations, where individuals within a cluster may be correlated due to unobserved shared factors. Estimators of the regression parameters in the marginal model are developed under an independence working assumption where the correlation across individuals within a cluster is completely unspecified. The estimators are consistent and asymptotically normal, and variance estimation may be achieved without specifying the form of the dependence across individuals. A simulation study evidences that the inferential procedures perform well with realistic sample sizes. The practical utility of the methods is illustrated with data from the European Bone Marrow Transplant Registry.", "grade": "A", "theme": "ch6_analysis_plan", "source": "openalex"}
{"key": "cleves2003", "title": "An Introduction to Survival Analysis Using Stata", "authors": ["Mario A. Cleves", "William Gould", "Roberto G. Gutierrez", "Yulia Marchenko"], "year": 2003, "venue": "RePEc: Research Papers in Economics", "doi": null, "url": "https://openalex.org/W1529206929", "abstract": "An Introduction to Survival Analysis Using Stata, Third Edition is the ideal tutorial for professional data analysts who want to learn survival analysis for the first time or who are well versed in survival analysis but are not as dexterous in using Stata to analyze survival data. This text also serves as a valuable reference to those readers who already have experience using Stata’s survival analysis routines. The third edition has been updated for Stata 11, and it includes a new chapter on competing-risks analysis. This chapter describes the problems posed by competing events (events that impede the failure event of interest), and covers estimation of cause-specific hazards and cumulative incidence functions. Other enhancements include the handling of missing values by multiple imputation in Cox regression, a new-to-Stata-11 system for specifying categorical (factor) variables and their interactions, three additional diagnostic measures for Cox regression, and a more efficient syntax for obtaining predictions and diagnostics after Cox regression.", "grade": "A", "theme": "ch6_analysis_plan", "source": "openalex"}
{"key": "mozumder2025", "title": "Calibration of cause-specific absolute risk for external validation using each cause-specific hazards model in the presence of competing events", "authors": ["S. I. Mozumder", "Sarah Booth", "Richard D Riley", "M. Rutherford", "Paul C Lambert"], "year": 2025, "venue": "Diagnostic and Prognostic Research", "doi": "10.1186/s41512-025-00197-5", "url": "https://doi.org/10.1186/s41512-025-00197-5", "abstract": "When developing/validating prognostic models, it is typical to assess calibration between predicted and observed risks — either in the development dataset or in an external sample. For competing risks data, correct specification of more than one model may be required to ensure well-calibrated predicted risks for the event of interest. Furthermore, interest may be in the predicted risks of the event of interest, competing events and all-causes. Therefore, calibration must be assessed simultaneously using various measures. We focus on the calibration of prediction models for external validation using a cause-specific hazards approach. We propose that miscalibration for cause-specific hazard models be assessed using components specific to each model through the complement of the cause-specific survival alongside the assessment of the calibration of the cause-specific absolute risks. We simulated a range of scenarios to illustrate how to identify which model(s) are mis-specified in an external validation setting. Calibration plots and calibration statistics (calibration slope, calibration-in-the-large) are presented alongside performance measures such as the Brier score and Index of Prediction Accuracy. We use pseudo-observations to calculate observed risks and generate a smooth calibration curve with restricted cubic splines. We fitted flexible parametric survival models to the simulated data to flexibly estimate baseline cause-specific hazards for the prediction of individual cause-specific absolute risks. Our simulations illustrate that miscalibration due to changes in the baseline cause-specific hazards in external validation data is better identified using components from each cause-specific model. A mis-calibrated model on one cause could lead to poor calibration of the predicted absolute risks for each cause of interest, including the all-cause absolute risk. This is because prediction of a single cause-specific absolute risk is impacted by effects of variables on the cause of interest and competing events. If accurate predictions for both all-cause and each cause-specific absolute risks are of interest, this is best achieved by developing and validating models via the cause-specific hazards approach. For each cause-specific model, researchers should evaluate calibration plots separately using the complement of the cause-specific survival function to reveal the cause of any miscalibration. However, this also requires careful consideration of dependent censoring which must be sufficiently accounted for.", "grade": "A", "theme": "ch6_analysis_plan", "source": "semanticscholar"}
{"key": "sava2025", "title": "Artificial intelligence in construction project management: Trends, challenges and future directions", "authors": ["Sezer Savaş"], "year": 2025, "venue": "Journal of Design for Resilience in Architecture and Planning", "doi": "10.47818/drarch.2025.v6i2165", "url": "https://doi.org/10.47818/drarch.2025.v6i2165", "abstract": "Contemporary construction projects are characterized by escalating complexity, voluminous data flows, and stringent sustainability requirements, rendering conventional project management methods increasingly inadequate. In response, artificial intelligence (AI) has emerged as a transformative enabler in construction project management, offering advanced capabilities in predictive analytics, process automation, and intelligent decision support. This paper explores the role of AI in the identified principal functions of construction project management, including time management, cost estimation, quality assurance, occupational health and safety, risk mitigation, resource optimization, and design management through a narrative literature review. Analysis demonstrates that AI-driven approaches significantly enhance operational efficiency and system resilience by enabling proactive identification of schedule delays, cost overruns, and safety hazards. For example, image-recognition systems integrated with Internet-of-Things sensors facilitate real-time monitoring of site conditions and adaptive response to disruptions, while neural-network models trained on historical project data yield more accurate cost forecasts than traditional estimation techniques. In the design management domain, generative design algorithms and AI-enhanced BIM integration have the potential to automate clash detection, optimize form and function, and generate innovative design alternatives that align with cost, energy, and sustainability objectives. Beyond efficiency gains, AI fosters a paradigm shift toward predictive, data-driven, and adaptive management practices that strengthen project resilience, enabling teams to anticipate, absorb, and recover from unforeseen challenges while improving project performance and sustainability. Critical barriers to widespread AI adoption are also identified in this study. Fragmented and non-standardized data ecosystems impede model training and interoperability with legacy systems, while organizational resistance and a shortage of professionals skilled in both AI and construction hinder implementation. Ethical and legal concerns—stemming from the “black-box” nature of many AI algorithms—further complicate accountability in safety-critical decisions. By synthesizing these challenges, the strategic role of AI is highlighted not only as a technological innovation but also as a catalyst for cultural and organizational transformation toward more resilient project delivery. Targeted future research directions include empirical validation of AI tools in live project environments, development of sector-specific AI frameworks tailored to the peculiarities of the construction industry, interdisciplinary collaboration among engineers, data scientists, and managers, and educational initiatives to upskill the workforce. Collectively, these steps will help bridge the gap between theoretical potential and real-world impact, positioning AI as a cornerstone of intelligent, resilient, sustainable, and high-performing construction project management.", "grade": "A", "theme": "ch6_analysis_plan", "source": "semanticscholar"}
{"key": "rufibach2024", "title": "Survival analysis for AdVerse events with VarYing follow-up times (SAVVY): summary of findings and assessment of existing guidelines", "authors": ["K. Rufibach", "J. Beyersmann", "T. Friede", "Claudia Schmoor", "Regina Stegherr"], "year": 2024, "venue": "Trials", "doi": "10.1186/s13063-024-08186-7", "url": "https://doi.org/10.1186/s13063-024-08186-7", "abstract": "Background The SAVVY project aims to improve the analyses of adverse events (AEs) in clinical trials through the use of survival techniques appropriately dealing with varying follow-up times and competing events (CEs). This paper summarizes key features and conclusions from the various SAVVY papers. Methods Summarizing several papers reporting theoretical investigations using simulations and an empirical study including randomized clinical trials from several sponsor organizations, biases from ignoring varying follow-up times or CEs are investigated. The bias of commonly used estimators of the absolute (incidence proportion and one minus Kaplan-Meier) and relative (risk and hazard ratio) AE risk is quantified. Furthermore, we provide a cursory assessment of how pertinent guidelines for the analysis of safety data deal with the features of varying follow-up time and CEs. Results SAVVY finds that for both, avoiding bias and categorization of evidence with respect to treatment effect on AE risk into categories, the choice of the estimator is key and more important than features of the underlying data such as percentage of censoring, CEs, amount of follow-up, or value of the gold-standard. Conclusions The choice of the estimator of the cumulative AE probability and the definition of CEs are crucial. Whenever varying follow-up times and/or CEs are present in the assessment of AEs, SAVVY recommends using the Aalen-Johansen estimator (AJE) with an appropriate definition of CEs to quantify AE risk. There is an urgent need to improve pertinent clinical trial reporting guidelines for reporting AEs so that incidence proportions or one minus Kaplan-Meier estimators are finally replaced by the AJE with appropriate definition of CEs.", "grade": "A", "theme": "ch6_analysis_plan", "source": "semanticscholar"}
{"key": "park2021b", "title": "Semiparametric regression on cumulative incidence function with interval-censored competing risks data and missing event types", "authors": ["Jun Park", "G. Bakoyannis", "Ying Zhang", "C. Yiannoutsos"], "year": 2021, "venue": "Biostatistics", "doi": "10.1093/biostatistics/kxaa052", "url": "https://doi.org/10.1093/biostatistics/kxaa052", "abstract": "Summary Competing risk data are frequently interval-censored, that is, the exact event time is not observed but only known to lie between two examination time points such as clinic visits. In addition to interval censoring, another common complication is that the event type is missing for some study participants. In this article, we propose an augmented inverse probability weighted sieve maximum likelihood estimator for the analysis of interval-censored competing risk data in the presence of missing event types. The estimator imposes weaker than usual missing at random assumptions by allowing for the inclusion of auxiliary variables that are potentially associated with the probability of missingness. The proposed estimator is shown to be doubly robust, in the sense that it is consistent even if either the model for the probability of missingness or the model for the probability of the event type is misspecified. Extensive Monte Carlo simulation studies show good performance of the proposed method even under a large amount of missing event types. The method is illustrated using data from an HIV cohort study in sub-Saharan Africa, where a significant portion of events types is missing. The proposed method can be readily implemented using the new function ciregic_aipw in the R package intccr.", "grade": "A", "theme": "ch6_analysis_plan", "source": "semanticscholar"}
{"key": "tanaka2024", "title": "Rare Event Approximation Between Subdistribution Hazard Ratio and Cause-specific Hazard Ratio in Survival Analysis With Competing Risks", "authors": ["Shiro Tanaka"], "year": 2024, "venue": "Journal of Epidemiology", "doi": "10.2188/jea.je20240063", "url": "https://doi.org/10.2188/jea.je20240063", "abstract": "Background Despite the fact that competing risks are inevitable in epidemiological and clinical studies, distinctions between the hazard ratio estimated by handling competing risks as censoring and the subditribution hazard ratio are often overlooked. Methods We derived quantitative relationships between subdistribution hazard ratio and cause-specific hazard ratio and derive an approximate calculation method to transform the two into each other. Numerical examinations of hypothetical six scenarios and published information of a randomized clinical trial of cholesterol-lowering therapy and a registry of acute myeloid leukemia were provided. Results General and approximate relationships under rare event assumptions between the two types of hazard ratio were given. The approximation formula is based on a survival ratio and has two possible applications. First, one can calculate a subdistribution hazard ratio from published information. Second, this formula allows sample size estimation that takes the presence of competing risks into account. Conclusion The distinction between the two types of hazard ratio can be addressed by focusing on two quantities. One is how the event of interest and competing risk is rare, and the other is the survival ratio.", "grade": "A", "theme": "ch6_analysis_plan", "source": "crossref"}
{"key": "hinchliffe2013", "title": "Flexible parametric modelling of cause-specific hazards to estimate cumulative incidence functions", "authors": ["Sally R. Hinchliffe", "Paul C. Lambert"], "year": 2013, "venue": "BMC Medical Research Methodology", "doi": "10.1186/1471-2288-13-13", "url": "https://openalex.org/W2027957809", "abstract": "BACKGROUND: Competing risks are a common occurrence in survival analysis. They arise when a patient is at risk of more than one mutually exclusive event, such as death from different causes, and the occurrence of one of these may prevent any other event from ever happening. METHODS: There are two main approaches to modelling competing risks: the first is to model the cause-specific hazards and transform these to the cumulative incidence function; the second is to model directly on a transformation of the cumulative incidence function. We focus on the first approach in this paper. This paper advocates the use of the flexible parametric survival model in this competing risk framework. RESULTS: An illustrative example on the survival of breast cancer patients has shown that the flexible parametric proportional hazards model has almost perfect agreement with the Cox proportional hazards model. However, the large epidemiological data set used here shows clear evidence of non-proportional hazards. The flexible parametric model is able to adequately account for these through the incorporation of time-dependent effects. CONCLUSION: A key advantage of using this approach is that smooth esti", "grade": "A", "theme": "ch6_analysis_plan", "source": "openalex"}
{"key": "scosyrev2020", "title": "Improved confidence intervals for a difference of two cause‐specific cumulative incidence functions estimated in the presence of competing risks and random censoring", "authors": ["Emil Scosyrev"], "year": 2020, "venue": "Biometrical Journal", "doi": "10.1002/bimj.201900060", "url": "https://doi.org/10.1002/bimj.201900060", "abstract": "<jats:title>Abstract</jats:title><jats:p>A cause‐specific cumulative incidence function (CIF) is the probability of failure from a specific cause as a function of time. In randomized trials, a difference of cause‐specific CIFs (treatment minus control) represents a treatment effect. Cause‐specific CIF in each intervention arm can be estimated based on the usual non‐parametric Aalen–Johansen estimator which generalizes the Kaplan–Meier estimator of CIF in the presence of competing risks. Under random censoring, asymptotically valid Wald‐type confidence intervals (CIs) for a difference of cause‐specific CIFs at a specific time point can be constructed using one of the published variance estimators. Unfortunately, these intervals can suffer from substantial under‐coverage when the outcome of interest is a rare event, as may be the case for example in the analysis of uncommon adverse events. We propose two new approximate interval estimators for a difference of cause‐specific CIFs estimated in the presence of competing risks and random censoring. Theoretical analysis and simulations indicate that the new interval estimators are superior to the Wald CIs in the sense of avoiding substantial under‐coverage with rare events, while being equivalent to the Wald CIs asymptotically. In the absence of censoring, one of the two proposed interval estimators reduces to the well‐known Agresti–Caffo CI for a difference of two binomial parameters. The new methods can be easily implemented with any software package producing point and variance estimates for the Aalen–Johansen estimator, as illustrated in a real data example.</jats:p>", "grade": "A", "theme": "ch6_analysis_plan", "source": "crossref"}
{"key": "ruan2008", "title": "Analyses of cumulative incidence functions via non‐parametric multiple imputation", "authors": ["Ping K. Ruan", "Robert J. Gray"], "year": 2008, "venue": "Statistics in Medicine", "doi": "10.1002/sim.3402", "url": "https://doi.org/10.1002/sim.3402", "abstract": "<jats:title>Abstract</jats:title><jats:p>We describe a non‐parametric multiple imputation method that recovers the missing potential censoring information from competing risks failure times for the analysis of cumulative incidence functions. The method can be applied in the settings of stratified analyses, time‐varying covariates, weighted analysis of case‐cohort samples and clustered survival data analysis, where no current available methods can be readily implemented. The method uses a Kaplan–Meier imputation method for the censoring times to form an imputed data set, so cumulative incidence can be analyzed using techniques and software developed for ordinary right censored survival data. We discuss the methodology and show from both simulations and real data examples that the method yields valid estimates and performs well. The method can be easily implemented via available software with a minor programming requirement (for the imputation step). It provides a practical, alternative analysis tool for otherwise complicated analyses of cumulative incidence of competing risks data. Copyright © 2008 John Wiley &amp; Sons, Ltd.</jats:p>", "grade": "A", "theme": "ch6_analysis_plan", "source": "crossref"}
{"key": "gebre2025", "title": "Time-dependent predictors of loss to follow-up in HIV care in low-resource settings: A competing risks approach", "authors": ["Tamrat Endebu Gebre", "Girma Taye", "W. Deressa"], "year": 2025, "venue": "PLoS ONE", "doi": "10.1371/journal.pone.0329132", "url": "https://doi.org/10.1371/journal.pone.0329132", "abstract": "Loss to follow-up (LTFU) remains a major challenge in HIV care, particularly in resource-limited settings. While several studies have identified its predictors, many have neglected the competing risks of transfer out and death, as well as the dynamic influence of these predictors over time. A retrospective cohort study was conducted among adult HIV patients who initiated antiretroviral therapy (ART) between 2019 and 2024. LTFU was a primary outcome, whereas transfer out and death were competing risks. A Fine‒Gray subdistribution hazard ratio (SHR) regression analysis identified LTFU predictors within a competing risk framework. An extended SHR model with a time‒covariate interaction term was used to examine the predictors’ time‒varying effects on LTFU risk. Data analysis was performed via STATA 17 and Python 3.9. In a cohort of 4,135 HIV patients (8,521.54 person-years of follow-up), the overall incidence of LTFU was 13.10 per 100 person-years (95% CI: 12.35–13.89), with cumulative risks of 15%, 25%, and 35% at 1, 3, and 5 years post-ART, respectively. The predictors of LTFU included younger age (15–24 years: aSHR = 1.51), male sex (aSHR = 1.24), incomplete address details (aSHR = 1.72), noninitiation/noncompletion of TPT (aSHR = 2.16), poor adherence (aSHR = 2.54), and undernutrition (aSHR = 2.03). While younger age (e.g., 15–24 years) was associated with an increased risk of LTFU at baseline (baseline aSHR = 1.36, p = 0.014), this association diminished over time (interaction aSHR = 0.54, p = 0.001). Undernutrition consistently predicted LTFU (baseline aSHR = 1.64, p < 0.001), with no significant time-dependent effect (interaction aSHR = 1.01, p = 0.903). In conclusion, this study highlights the high incidence of LTFU among HIV patients and its key predictors. Notably, age has a significant time-dependent effect, with its influence on the risk of LTFU being most pronounced during the early stage of ART initiation, whereas nutritional status remains a consistent predictor of LTFU over time.", "grade": "A", "theme": "ch6_analysis_plan", "source": "semanticscholar"}
{"key": "pintilie2006", "title": "Competing Risks: A Practical Perspective", "authors": ["Melania Pintilie"], "year": 2006, "venue": null, "doi": null, "url": "https://openalex.org/W179935622", "abstract": "Preface. Acknowledgements. 1. Introduction. 1.1 Historical notes. 1.2 Defining competing risks. 1.3 Use of the Kaplan-Meier method in the presence of competing risks. 1.4 Testing in the competing risk framework. 1.5 Sample size calculation. 1.6 Examples. 1.6.1 Tamoxifen trial. 1.6.2 Hypoxia study. 1.6.3 Follicular cell lymphoma study. 1.6.4 Bone marrow transplant study. 1.6.5 Hodgkin's disease study. 2. Survival - basic concepts. 2.1 Introduction. 2.2 Definitions and background formulae. 2.2.1 Introduction. 2.2.2 Basic mathematical formulae. 2.2.3 Common parametric distributions. 2.2.4 Censoring and assumptions. 2.3 Estimation and hypothesis testing. 2.3.1 Estimating the hazard and survivor functions. 2.3.2 Nonparametric testing: log-rank and Wilcoxon tests. 2.3.3 Proportional hazards model. 2.4 Software for survival analysis. 2.5 Closing remarks. 3. Competing risks - definitions. 3.1 Recognizing competing risks. 3.1.1 Practical approaches. 3.1.2 Common endpoints in medical research. 3.2 Two mathematical definitions. 3.2.1 Competing risks as bivariate random variable. 3.2.2 Competing risks as latent failure times. 3.3 Fundamental concepts. 3.3.1 Competing risks as bivariate random ", "grade": "B", "theme": "ch6_analysis_plan", "source": "openalex"}
{"key": "dise", "title": "DISE: A Dynamic Integrated Space-Economy Model for Orbital Debris Mitigation Policy Evaluation (2025)", "authors": [], "year": null, "venue": null, "doi": "10.1007/s10640-025-01003-y", "url": "https://doi.org/10.1007/s10640-025-01003-y", "abstract": null, "grade": "A", "theme": "ch7_discussion", "source": "hall-of-shoulders:fogel"}
{"key": "zancan", "title": "Evolving governance in the space sector: From Legacy Space to New Space models (Zancan, Paravano, Locatelli & Trucco 2024)", "authors": ["E. Zancan", "A. Paravano", "G. Locatelli", "P. Trucco"], "year": null, "venue": null, "doi": "10.1016/j.actaastro.2024.09.005", "url": "https://doi.org/10.1016/j.actaastro.2024.09.005", "abstract": "Governance evolution from legacy to new-space delivery models, relevant to launch-availability and acquisition-era effects on schedule.", "grade": "A", "theme": "ch7_discussion", "source": "hall-of-shoulders:fogel"}
{"key": "akinyokun2025", "title": "A Review of the Application of Decision Tree Analysis and Artificial Neural Networks in Project Management", "authors": ["Olusina Temidayo Akinyokun", "Onifade. Morakinyo Kehinde", "Adegoke Michael Abejide"], "year": 2025, "venue": "Jurnal Teknik Industri: Jurnal Hasil Penelitian dan Karya Ilmiah dalam Bidang Teknik Industri", "doi": "10.24014/jti.v11i1.16480", "url": "https://doi.org/10.24014/jti.v11i1.16480", "abstract": "The advancement of computing and communication technologies has fueled the growth of Information Technology (IT), with Artificial Intelligence (AI) emerging as a transformative force in modernizing project management practices. This study explores the application of two prominent AI techniques—Decision Tree Analysis (DTA) and Artificial Neural Networks (ANN)—in improving project planning and control. A review of empirical studies highlights the limitations of conventional tools such as Gantt charts and the Critical Path Method (CPM) in managing complex project variables, often resulting in cost overruns and schedule delays. In contrast, DTA and ANN demonstrate superior predictive accuracy, decision support, and adaptability capabilities. DTA offers transparent and structured decision-making models, while ANN excels in pattern recognition and outcome forecasting. The findings underscore that integrating these AI tools enhances project efficiency, cost estimation, and time management, establishing AI as a critical asset for future project success.Keywords: Artificial Intelligence, Decision Tree Analysis, Artificial Neural Networks, Project Planning, Project Control", "grade": "A", "theme": "ch7_discussion", "source": "semanticscholar"}
{"key": "budzier2024", "title": "The Oxford Olympics Study 2024: Are Cost and Cost Overrun at the Games Coming Down?", "authors": ["Alexander Budzier", "Bent Flyvbjerg"], "year": 2024, "venue": "Social Science Research Network", "doi": "10.2139/ssrn.4849892", "url": "https://doi.org/10.2139/ssrn.4849892", "abstract": "The present paper is an update of the\"Oxford Olympics Study 2016\"(Flyvbjerg et al. 2016). We document that the Games remain costly and continue to have large cost overruns, to a degree that threatens their viability. The IOC is aware of the problem and has initiated reform. We assess the reforms and find: (a) Olympic costs are statistically significantly increasing; prior analysis did not show this trend; it is a step in the wrong direction. (b) Cost overruns were decreasing until 2008, but have increased since then; again a step in the wrong direction. (c) At present, the cost of Paris 2024 is USD 8.7 billion (2022 level) and cost overruns is 115% in real terms; this is not the cheap Games that were promised. (d) Cost overruns are the norm for the Games, past, present, and future; they are the only project type that never delivered on budget. We assess a new IOC policy of reducing cost by reusing existing venues instead of building new ones. We find that reuse did not have the desired effect for Tokyo 2020 and also look ineffective for Paris 2024. Finally, we recommend that the Games look to other types of megaprojects for better data, better forecasting, and how to generate the positive learning curves that are necessary for bringing costs and overrun down. Only if this happens are Los Angeles 2028 and Brisbane 2032 likely to live up to the IOC's intentions of a more affordable Games that more cities will want to host.", "grade": "B", "theme": "ch7_discussion", "source": "semanticscholar"}
{"key": "zaki2026", "title": "Factors Affecting Schedule Delay and Cost Overrun in Egyptian Construction Projects", "authors": ["Ammar Zaki"], "year": 2026, "venue": null, "doi": "10.2139/ssrn.6103586", "url": "https://doi.org/10.2139/ssrn.6103586", "abstract": null, "grade": "B", "theme": "ch7_discussion", "source": "crossref"}
{"key": "precious2025", "title": "Infrastructure project cost overrun and schedule delay in Ghana: Is it an issue of resource misallocation or financial constraints?", "authors": ["Doe Precious"], "year": 2025, "venue": "Project Leadership and Society", "doi": "10.1016/j.plas.2025.100188", "url": "https://doi.org/10.1016/j.plas.2025.100188", "abstract": null, "grade": "A", "theme": "ch7_discussion", "source": "crossref"}
{"key": "aliyev2025", "title": "The AI and Quantum Era: Transforming Project Management Practices", "authors": ["A. Aliyev"], "year": 2025, "venue": "Journal of Future Artificial Intelligence and Technologies", "doi": "10.62411/faith.3048-3719-59", "url": "https://doi.org/10.62411/faith.3048-3719-59", "abstract": "Project management is changing drastically due to the integration of artificial intelligence (AI) and quantum computing (QC), redefining traditional methods. This study explores Quantum AI (QAI) and AI-driven solutions to tackle enduring issues, including resource inefficiencies, schedule delays, and budget overruns. These technologies significantly enhance project outcomes by leveraging predictive analytics, dynamic scheduling, and high-dimensional optimization. A comparative analysis of prominent case studies, including the Crossrail Project, East Side Access, and the Montreal Olympics, highlights the superior performance of AI and QAI techniques compared to conventional methods. The study shows that QAI can cut delays by 60%, optimize resource allocation with 83% efficiency, and eliminate cost overruns by up to 40% using Monte Carlo simulations and Failure Mode Effects Analysis. These results demonstrate that quantum artificial intelligence is a ground-breaking tool for handling intricate, interconnected project settings. Additionally, this study emphasizes how QAI is scalable and applicable across industries, especially in fields that need real-time optimization and high-dimensional data processing. The proposed hybrid quantum-classical paradigm provides practical solutions and sets a benchmark for efficiency, scalability, and risk mitigation in project management.", "grade": "A", "theme": "ch7_discussion", "source": "semanticscholar"}
{"key": "flyvbjerg2007", "title": "Megaproject policy and planning: Problems, causes, cures", "authors": ["Bent Flyvbjerg"], "year": 2007, "venue": "VBN Forskningsportal (Aalborg Universitet)", "doi": null, "url": "https://openalex.org/W1832657426", "abstract": "This paper focuses on problems in megaproject policy and planning and their causes and possible cures.After considerations of methodology, the paper first identifies as a main problem in megaproject development pervasive misinformation about the costs, benefits, and risks involved.A consequence of misinformation is cost overruns, benefit shortfalls, and waste.Second, the paper explores the causes of misinformation and finds that political-economic explanations best account for the available evidence: planners and promoters deliberately misrepresent costs, benefits, and risks in order to increase the likelihood that it is their projects, and not the competition's, that gain approval and funding.This results in the \"survival of the unfittest,\" where often it is not the best projects that are built, but the most misrepresented ones.Finally, the paper presents measures for reforming megaproject policy and planning with a focus on better planning methods and improved governance structures, the latter being more important.", "grade": "A", "theme": "ch7_discussion", "source": "openalex"}
{"key": "lekraik2025", "title": "Advancing Digital Project Management Through AI: An Interpretable POA-LightGBM Framework for Cost Overrun Prediction", "authors": ["Jalal Meftah Mohamed Lekraik", "Opeoluwaseun Ojekemi"], "year": 2025, "venue": "Syst.", "doi": "10.3390/systems13121047", "url": "https://doi.org/10.3390/systems13121047", "abstract": "Cost overruns remain one of the most persistent challenges in construction and infrastructure project management, often undermining efficiency, sustainability, and stakeholder trust. With the rise of digital transformation, artificial intelligence (AI) and machine learning (ML) provide new opportunities to enhance predictive decision-making and strengthen project control. This study introduces a digital project management framework that integrates the Pelican Optimization Algorithm (POA) with Light Gradient Boosting Machine (LGBM) to deliver reliable and interpretable cost overrun forecasting. The proposed POA-LightGBM model leverages metaheuristic-driven hyperparameter optimization to improve predictive performance and generalization. A comprehensive evaluation using multiple error metrics Coefficient of Determination (R2), Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), and Mean Absolute Percentage Error (MAPE) demonstrates that POA-LGBM significantly outperformed baseline LGBM and alternative metaheuristic configurations, achieving an average R2 of 0.9786. To support transparency in digital project environments, SHapley Additive exPlanations (SHAPs) were employed to identify dominant drivers of cost overruns, including actual project cost, energy consumption, schedule deviation, and material usage. By embedding AI-enabled predictive analytics into digital project management practices, this study contributes to advancing digital transformation in project delivery, offering actionable insights for cost control, risk management, and sustainable infrastructure development.", "grade": "A", "theme": "ch7_discussion", "source": "semanticscholar"}
{"key": "majeed2025", "title": "Evaluating Cost Estimation and Budgeting Challenges in Public Health and Education Infrastructure Projects", "authors": ["Dr. Muhammad Imran Majeed", "Dr. Abdullah Hammad", "Dr Sahar Munir", "Rida Maqsood", "Isha Safdar"], "year": 2025, "venue": "Social Science Review Archives", "doi": "10.70670/sra.v3i4.1385", "url": "https://doi.org/10.70670/sra.v3i4.1385", "abstract": "Persistent cost overruns and budgetary deviations continue to undermine the delivery of public infrastructure projects worldwide, despite decades of reform in project management and public financial management systems. While extensive scholarship has examined cost estimation failures in large transportation and energy megaprojects, comparatively limited attention has been paid to public health and education infrastructure, sectors that are central to human capital development and social welfare. This paper addresses this gap by critically evaluating cost estimation and budgeting challenges in public health and education infrastructure projects from a global perspective.Drawing on a comprehensive synthesis of international fiscal data, infrastructure performance studies, and institutional analyses, the study examines how macro-fiscal constraints, budget allocation frameworks, and governance arrangements shape cost estimation practices and project cost performance in hospitals, schools, and higher education facilities. The paper develops an integrated conceptual framework linking fiscal structures, budget rigidity, behavioral biases, and institutional capacity to systematic underestimation and subsequent cost escalation. Empirical evidence from global datasets and sector-specific studies reveals that cost overruns in health and education infrastructure are pervasive across income groups, with average overruns frequently exceeding 20–40%, reflecting structural rather than context-specific failures.The findings demonstrate that cost estimation inaccuracies are not merely technical errors but are deeply embedded in political and institutional incentive systems that prioritize project approval over delivery realism. By explicitly connecting cost estimation processes to public budgeting mechanisms, the study advances infrastructure governance theory beyond project-level explanations. The paper concludes by outlining policy-relevant implications for improving estimation accuracy, strengthening budget credibility, and enhancing value for money in public health and education infrastructure investment.", "grade": "A", "theme": "ch7_discussion", "source": "semanticscholar"}