Time to adjust: Improving replicability in experimental psychology by adjustment for evident selective inference

Abstract

The field of psychological sciences has been grappling with the replicability crisis. Various issues have been identified as potential sources of this problem. We bring to light a potential source that has largely been overlooked and demonstrate its significant contribution to the problem: the practice of multiple comparisons. We analyzed 88 papers from the Reproducibility Project in Psychology and found that multiple results are commonly reported in a single paper, ranging from 4 to 730 (M=77.7), without multiple comparison adjustments. We retroactively applied such an adjustment using a hierarchical FDR controlling procedure (TreeBH; Bogomolov et al., 2021). 21 of 88 results were deemed insignificant after adjustment. Twenty of these 21 results indeed failed to replicate, constituting over a third of the non-replicable findings, while maintaining 97% power. We propose that this should become a common practice as an essential means to increase replicability in experimental psychology.