Hedges’ g is one of the family of mean difference effect sizes used to evaluate the magnitude of the difference between the means of two groups. Hedges’ g is used for power analysis in preparation for a study, in conjunction with null hypothesis testing to help determine whether a significant p value of the null hypothesis test is of practical importance, and may be used in meta-analyses to compare and combine the results of different studies. In this entry, formulas to calculate the statistic and its confidence interval are presented, followed by examples.

Mean Difference Effect Size

Mean differences are used to compare the size of the outcomes between groups. The measured magnitude of a mean difference is called an effect size. An effect size indicates how ...

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