---
title: "Replication crisis"
chunk: 4/15
source: "https://en.wikipedia.org/wiki/Replication_crisis"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:45:08.741659+00:00"
instance: "kb-cron"
---

=== In psychology ===
Several factors have combined to put psychology at the center of the conversation. Some areas of psychology once considered solid, such as social priming and ego depletion, have come under increased scrutiny due to failed replications. Much of the focus has been on social psychology, although other areas of psychology such as clinical psychology, developmental psychology, and educational research have also been implicated.
In August 2015, the first open empirical study of reproducibility in psychology was published, called The Reproducibility Project: Psychology. Coordinated by psychologist Brian Nosek, researchers redid 100 studies in psychological science from three high-ranking psychology journals (Journal of Personality and Social Psychology, Journal of Experimental Psychology: Learning, Memory, and Cognition, and Psychological Science). Of 97 original studies with significant effects, 36% replicated successfully (p value below 0.05), with effect sizes averaging half the original magnitude. Among non-replications, 25% directly contradicted the original while 49% were inconclusive due to underpowered designs. The same paper examined the reproducibility rates and effect sizes by journal and discipline. Study replication rates were 23% for the Journal of Personality and Social Psychology, 48% for Journal of Experimental Psychology: Learning, Memory, and Cognition, and 38% for Psychological Science. Studies in the field of cognitive psychology had a higher replication rate (50%) than studies in the field of social psychology (25%). This inconclusiveness reflected inadequate statistical power: replication samples were approximately 40% the size of the originals.
A study published in 2018 in Nature Human Behaviour replicated 21 social and behavioral science papers from Nature and Science, finding that only about 62% could successfully reproduce original results.
Similarly, in a study conducted under the auspices of the Center for Open Science, a team of 186 researchers from 60 laboratories (representing 36 nationalities from six continents) conducted replications of 28 classic and contemporary findings in psychology. The study's focus was not only whether the original papers' findings replicated but also the extent to which findings varied as a function of variations in samples and contexts. Overall, 50% of findings failed to replicate despite large sample sizes. When findings did replicate, they consistently replicated across most samples. When they failed, they consistently failed across contexts, suggesting contextual sensitivity was not the primary driver of replication failures. This evidence is inconsistent with a proposed explanation that failures to replicate in psychology are likely due to changes in the sample between the original and replication study.
Results of a 2022 study suggest that many earlier brain–phenotype studies ("brain-wide association studies" (BWAS)) produced invalid conclusions as the replication of such studies requires samples from thousands of individuals due to small effect sizes.

=== In medicine ===

Of 49 medical studies from 1990 to 2003 with more than 1000 citations, 92% found that the studied therapies were effective. Of these studies, 16% were contradicted by subsequent studies, 16% had found stronger effects than did subsequent studies, 44% were replicated, and 24% remained largely unchallenged. A 2011 analysis by researchers with pharmaceutical company Bayer found that, at most, a quarter of Bayer's in-house findings replicated the original results. But the analysis of Bayer's results found that the results that did replicate could often be successfully used for clinical applications.
In a 2012 paper, C. Glenn Begley, a biotech consultant working at Amgen, and Lee Ellis, a medical researcher at the University of Texas, found that only 11% of 53 pre-clinical cancer studies had replications that could confirm conclusions from the original studies. In late 2021, The Reproducibility Project: Cancer Biology examined 53 top papers about cancer published between 2010 and 2012 and showed that among studies that provided sufficient information to be redone, the effect sizes were 85% smaller on average than the original findings. A survey of cancer researchers found that half of them had been unable to reproduce a published result. Another report estimated that almost half of randomized controlled trials contained flawed data (based on the analysis of anonymized individual participant data (IPD) from more than 150 trials).

=== In other disciplines ===

==== In nutrition science ====
In nutrition science, for most food ingredients, there were studies that found that the ingredient has an effect on cancer risk. Specifically, out of a random sample of 50 ingredients from a cookbook, 80% had articles reporting on their cancer risk. Statistical significance decreased for meta-analyses.

==== In economics ====
Economics has lagged behind other social sciences and psychology in its attempts to assess replication rates and increase the number of studies that attempt replication. A 2016 study in the journal Science replicated 18 experimental studies published in two leading economics journals, The American Economic Review and the Quarterly Journal of Economics, between 2011 and 2014. It found that approximately 61% of studies successfully replicated, though the replicated effect sizes were only 66% of the original reported effect sizes on average, suggesting that the original studies' effect sizes were inflated. About 20% of studies published in The American Economic Review are contradicted by other studies despite relying on the same or similar data sets. A study of empirical findings in the Strategic Management Journal found that about 30% of 27 retested articles showed statistically insignificant results for previously significant findings, whereas about 4% showed statistically significant results for previously insignificant findings.

==== In water resource management ====
A 2019 study in Scientific Data estimated with 95% confidence that of 1,989 articles on water resources and management published in 2017, study results might be reproduced for only 0.6% to 6.8%, largely because the articles did not provide sufficient information to allow for replication.