Finally, the reviewed studies were largely underpowered, which can explain both failures to replicate previous findings and aberrant large effects (Maxwell, 2004). The average sample included in the meta-analysis comprised 41 total participants (i.e., 20.5 participants per group). At 80% power, this sample size would only be sensitive to group differences greater than or equal to 0.90 standard deviations, effects far larger than the mean sizes estimated here. Future alcohol-challenge studies will require larger samples.
