Informative and Non-Informative Effect Sizes. This figure is adapted from Armitage and Berry. Each open diamond denotes a hypothetical meta-analytic summary statistic, and the horizontal segments denote 95% confidence intervals. The dashed vertical line indicates the effect size that was determined a priori to represent the minimum effect size that is considered clinically important. A meta-analytic summary statistic is considered informative if its confidence interval either excludes 0 or excludes a clinically important effect (or both). Thus, meta-analyses A through D each show informative results, whereas meta-analysis E shows a non-informative result.