Replication success under questionable research practices – a simulation study

Increasing evidence suggests that the reproducibility and replicability of scientific findings is threatened by researchers employing questionable research practices (QRPs) in order to achieve statistically significant results. Numerous metrics have been developed to determine replication success but it has not yet been investigated how well those metrics perform in the presence of QRPs. This paper aims to compare the performance of different metrics quantifying replication success in the presence of four types of QRPs: cherry picking of outcomes, questionable interim analyses, questionable inclusion of covariates, and questionable subgroup analyses. Our results show that the metric based on the version of the sceptical p-value that is recalibrated in terms of effect size performs better in maintaining low values of overall type-I error rate, but often requires larger replication sample sizes compared to metrics based on significance, the controlled version of the sceptical p-value, meta-analysis or Bayes factors, especially when severe QRPs are employed.