Definition

Replication crisis

The finding, across several fields, that many published results fail to reproduce when independently repeated — and the reform movement it triggered.

Large-scale replication projects in the 2010s found substantial fractions of celebrated findings shrinking or vanishing on repetition, with psychology and biomedicine most publicly affected. Diagnosed causes: underpowered studies, flexible analyses (p-hacking), publication bias, and career incentives favoring novelty over verification.

The reform toolkit is now mainstream: preregistration, larger samples justified by power analysis, data and code sharing, registered reports, and replication as publishable work. For readers, the durable lesson is calibration — single studies are evidence, not facts.