Analysis of Bayesian posterior significance and effect size indices for the two-sample t-test to support reproducible medical research

摘要

In randomised clinical trials (RCT), the two-sample Student’s and Welch’s -test is one of the most popular statistical procedures conducted. The goal often can be defined to test the efficacy of a new treatment or medication and investigate the size of an effect. Common settings use a treatment and control group, and the goal is to measure differences in a response variable like blood pressure. The gold standard in medical research for deciding if a new treatment or drug was more effective than the control treatment or drug is the -value. The -value states if the researcher can deem the observed difference significant, that means unlikely to have occurred under the assumption of the null hypothesis. The dominance of -values when comparing two groups in medical (and other) research is overwhelming: Nuijten et al. [ ] showed in a meta-analysis that of 258105 -values reported in journals between 1985 and 2013, 26% belonged to a -statistic, see also Wetzels et al. [ ].