Researchers have suggested the use of credibility intervals for identifying moderator effects in meta‐analysis. In the present study, the accuracy of decisions derived from credibility intervals was determined from Monte Carlo generated correlations based on two series of meta‐analyses, one containing 20 studies and the other, 100 studies. Within each study, the responses of 100 subjects were simulated. Although in some marginal cases the accuracy measures (Type I error rate and power) from the credibility intervals were better than those derived from the SH‐75 per cent and U rules, the former technique was generally found to be a poor indicator of heterogeneity or homogeneity. Finally, the concept of a large interval was discussed and a rule of thumb for using it to detect moderators was suggested.