Preprint of a New Paper Comparing p-curve and p-uniform

Our team member Robbie van Aert recently got his paper accepted for publication in Perspectives on Psychological Science, together with Jelte Wicherts and Marcel van Assen. The abstract: Because evidence of publication bias in psychology is overwhelming, it is important to develop techniques that correct meta-analytic estimates for publication bias. Van Assen, Van Aert, and Wicherts (2015) and Simonsohn, Nelson, and Simmons (2014a) developed p-uniform and p-curve, respectively. The methodology on which these methods are based has great promise for providing accurate meta-analytic estimates in the presence of publication bias. However, we show that in some situations p-curve behaves erratically while p-uniform may yield implausible negative effect size estimates. Moreover, we show that (and explain why) p-curve and p-uniform overestimate effect size under moderate to large heterogeneity, and may yield unpredictable bias when researchers employ p-hacking. We offer hands-on recommendations on applying and interpreting results of meta-analysis in general and p-uniform and p-curve in particular. Both methods as well as traditional methods are applied to a meta-analysis on the effect of weight on judgments of importance. We offer guidance for applying p-uniform or p-curve using R and a user-friendly web application for applying p-uniform (

An interesting read for anyone using these methods or interested in applying these methods! The paper will be published in a special issue on Methods and Practices.

Download the preprint here.