Publication bias in psychology: a diagnosis based on the correlation between effect size and sample size.

ABSTRACT:

Background

The p value obtained from a significance test provides no information about the magnitude or importance of the underlying phenomenon. Therefore, additional reporting of effect size is often recommended. Effect sizes are theoretically independent from sample size. Yet this may not hold true empirically: non-independence could indicate publication bias.

Methods

We investigate whether effect size is independent from sample size in psychological research. We randomly sampled 1,000 psychological articles from all areas of psychological research. We extracted p values, effect sizes, and sample sizes of all empirical papers, and calculated the correlation between effect size and sample size, and investigated the distribution of p values.

Results

We found a negativ

SUBMITTER: Kuhberger A 

PROVIDER: S-EPMC4156299 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature