Publication Bias: Why the Published Evidence Overstates Almost Everything

Summary

The studies you get to see are a **biased sample** of the studies that were run: positive, novel, and exciting results get published and promoted while null results vanish into the file drawer, trials switch their outcomes after the fact, and industry-funded studies disproportionately favour the sponsor — so the published literature **systematically overstates** how well things work, and even a meta-analysis is only as honest as the trials that reached print.