Replication

There’s been a lot of commentary on a recent study by the Replication Project that attempted to replicate 100 published studies in psychology, all of which found statistically significant effects of some kind. The results were pretty dismal. Only about one-third of the replications observed a statistically significant effect, and the average effect size was about half that originally reported.

Unfortunately, most of the discussion of this study I’ve seen, notably in the New York Times, has missed the key point, namely the problem of publication bias.