Replication Crisis

The replication crisis is the discovery that many published research findings do not hold when other researchers try to repeat the same study. In psychology, medicine, economics, and other fields, high-profile results have failed to replicate. The causes include publication bias (negative results don't get published), p-hacking (researchers try many analyses until one is "significant"), small samples (underpowered studies produce fragile results), and incentive misalignment (careers reward novel, positive findings). The crisis doesn't mean all science is wrong — it means that a single study, especially a surprising one, should be treated as provisional until replicated.

The mental model applies beyond academia. In business and investing, "studies show" and "research says" often rest on single papers or internal analyses that were never replicated. The discipline is to treat first findings as hypotheses, not truths; to prefer replicated and pre-registered work; and to be suspicious of results that are too good, too neat, or from small samples. When you base decisions on evidence, ask: has this been replicated? Was the analysis pre-registered? What's the base rate for replication in this domain?