A simulation study of the strength of evidence in the recommendation of medications based on two trials with statistically significant results.

ABSTRACT: A typical rule that has been used for the endorsement of new medications by the Food and Drug Administration is to have two trials, each convincing on its own, demonstrating effectiveness. "Convincing" may be subjectively interpreted, but the use of p-values and the focus on statistical significance (in particular with p < .05 being coined significant) is pervasive in clinical research. Therefore, in this paper, we calculate with simulations what it means to have exactly two trials, each with p < .05, in terms of the actual strength of evidence quantified by Bayes factors. Our results show that different cases where two trials have a p-value below .05 have wildly differing Bayes factors. Bayes factors of at least 20 in favor of the alternative hypothesis are not necessarily achieved and th

SUBMITTER: van Ravenzwaaij D 

PROVIDER: S-EPMC5342224 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature