Kevin Lang argues in NBER wp 31666: When economists analyze a well-conducted RCT or natural experiment and find a statistically significant effect, they conclude the null of no effect is unlikely to be true. But how frequently is this conclusion warranted? The answer depends on the proportion of tested nulls that are true and the power of the tests. I model the distribution of t-statistics in leading economics journals. Using my preferred model, 65% of narrowly rejected null hypotheses...
Read More »Doubts about Empirical Research
The Economist reports about research by Paul Smaldino and Richard McElreath indicating that studies in psychology, neuroscience and medicine have low statistical power (the probability to correctly reject a null hypothesis). If, nevertheless, almost all published studies contain significant results (i.e., rejections of null hypotheses), then this is suspicious. Furthermore, Smaldino and McElreath’s research suggests that the process of replication, by which published results are tested...
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