ArticleAmerican journal of epidemiology2025
Trends in the distribution of P values in epidemiology journals: a statistical, P-curve, and simulation study.
Article in American journal of epidemiology, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
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12 authors.
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Abstract
Epidemiologists have advocated for reporting confidence intervals and deemphasizing P values to address long-standing concerns about null-hypothesis statistical-significance testing, P hacking, and reproducibility. It is unknown if efforts to reduce reliance on P values have altered the distribution of P values. For 21 332 abstracts published 2000 to 2024 in 4 major epidemiology journals, two-sided P values (N = 25 288) were calculated from estimates and confidence intervals scraped using ChatGPT's 4o-mini model. We evaluated trends over time to determine whether the empirical distribution of P values changed. We fitted to expected P-value distributions and simulated these distributions with and without assuming changes in statistical power over time. Average P values decreased from 2000 to 2024; the fraction of P values just below the .05 threshold also decreased. Fits to models indicate that statistical power increased. Increasing power would reduce average P value while also decreasing P values near the .05 threshold-precisely the trends observed in epidemiology journals. Although the frequency of P values near the .05 threshold has declined modestly, this likely reflects increases in statistical power rather than decreases in P hacking.
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