Jack Fitzgerald
Postdoctoral Scholar, SCRDP/ Heart Disease Prevention
Bio
I am a Postdoctoral Scholar at Stanford University, based in the Meta-Research Innovation Center at Stanford. I retain a guest affiliation with the Department of Ethics, Governance, and Society at Vrije Universiteit Amsterdam, where I received my PhD in Economics and Business Administration cum laude. I am also a Fellow of the Institute for Replication.
Current Research and Scholarly Interests
I work on issues in applied econometrics, replication, and metascience, and I am dedicated to improving methods in scientific research. My research can broadly be categorized as follows:
Replication-based methods research
I work to evidence the importance of methodological improvements through re-analyzing the replication data of large numbers of published articles that use similar methods. My job market paper evidences the importance of equivalence testing in 81 articles that advertise null results, my paper on log-like specifications re-analyzes 46 articles that use such specifications, and my paper on manipulation tests in regression discontinuity design re-analyzes 36 published articles using such designs.
Equivalence testing and practical significance testing
My job market paper introduces methods that can provide statistically significant evidence that economic relationships are practically equal to zero. In their absence, error rates in top economics journals are quite high. I’ve also employed these tests in empirical applications, such as my article in Journal of Business Ethics, and in extended methodological applications, such as in my tutorial on three-sided testing.
Robustness tests for causal inference
I work on methods for testing critical assumptions in causal designs, including manipulation tests in regression discontinuity design and hypothetical bias experiments
Replication
I have reproduced over 140 papers throughout my PhD, and I have published replication work in Nature Human Behaviour, Journal of Political Economy: Microeconomics, and two times in the Proceedings of the National Academy of Sciences. I have several comments under invited (re)submission concerning publications in American Economic Journal: Applied Economics and Management Science.
All Publications
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AI-assisted teams outperform AI-led teams but not human-only teams in assessing research reproducibility in quantitative social science.
Proceedings of the National Academy of Sciences of the United States of America
2026; 123 (22): e2524747123
Abstract
Large Language Models (LLMs) such as ChatGPT are transforming how scientists conduct and validate research, offering promise as tools to improve scientific reproducibility. However, computational reproducibility and error detection remain expensive and labor-intensive. We experimentally test how collaboration between researchers and LLM assistants influences the reproduction of quantitative social science findings across different levels of AI autonomy. We randomly assigned 288 researchers to 103 teams working under three conditions: human-only, AI-assisted (using ChatGPT as a collaborative tool), or AI-led (ChatGPT operating with minimal human oversight). Teams reproduced published results from leading social science journals, detected coding errors, and proposed robustness checks. Human-only and AI-assisted teams achieved comparable reproduction rates (94% vs. 91%) and performed similarly on most outcomes, except human-only teams identified significantly more major coding errors. Both substantially outperformed AI-led teams, which achieved only a 37% reproduction rate, detected fewer errors across all categories, proposed weaker robustness checks, and required more time. This autonomous approach, however, likely represents only a lower bound of AI capabilities. Despite rapid model advances, expert human judgment currently remains indispensable for reliable empirical verification. While AI assistance did not degrade most outcomes, it provided no measurable advantages and was associated with reduced detection of major errors. However, the 37% autonomous reproduction rate indicates that AI could provide value in settings where scale or cost constraints preclude human review of papers, even though general-purpose LLMs offer no immediate advantages for human-supervised verification.
View details for DOI 10.1073/pnas.2524747123
View details for PubMedID 42207915
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AI-assisted teams outperform AI-led teams but not human-only teams in assessing research reproducibility in quantitative social science
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2026; 123 (22)
View details for Web of Science ID 001821087300001
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Three-Sided Testing to Establish Practical Significance: A Tutorial
ADVANCES IN METHODS AND PRACTICES IN PSYCHOLOGICAL SCIENCE
2026; 9 (2)
View details for DOI 10.1177/25152459251412435
View details for Web of Science ID 001751066400001
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Revisiting the cognitive advantages of professional soccer players
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2026; 123 (8): e2515523123
View details for DOI 10.1073/pnas.2515523123
View details for Web of Science ID 001728252500001
View details for PubMedID 41706893
View details for PubMedCentralID PMC12933045
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Imputations, inverse hyperbolic sines and impossible values
NATURE HUMAN BEHAVIOUR
2026; 10 (2): 239-242
View details for DOI 10.1038/s41562-025-02347-7
View details for Web of Science ID 001656594800001
View details for PubMedID 41507633
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Identifying the impact of hypothetical stakes on experimental outcomes and treatment effects
EXPERIMENTAL ECONOMICS
2026
View details for DOI 10.1017/eec.2025.10035
View details for Web of Science ID 001654662100001
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US states that mandated COVID-19 vaccination see higher, not lower, take-up of COVID-19 boosters and flu vaccines
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2024; 121 (41): e2403758121
View details for DOI 10.1073/pnas.2403758121
View details for Web of Science ID 001408433200004
View details for PubMedID 39348537
View details for PubMedCentralID PMC11474055
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Is There a Foreign Language Effect on Workplace Bribery Susceptibility? Evidence from a Randomized Controlled Vignette Experiment
JOURNAL OF BUSINESS ETHICS
2025; 197 (1): 73-97
View details for DOI 10.1007/s10551-024-05731-x
View details for Web of Science ID 001246394400002
https://orcid.org/0000-0002-0322-5104