An Analysis of the Effects That Several Design Variables Have on the Accuracy and Precision of Glass’ Delta and Hedges’ g

Effect size is the standardized effect that some treatment has on a sample of a population. In particular, Hedges\u27 g and Glass delta are mean difference effect size estimators that are used to compute the effect sizes found in an experimental situation. A confidence interval is an interval placed around a point estimate that indicates the precision with which the point estimate can be made. This paper provides an explanation of the concept of effect size estimation and confidence interval calculation, the different methods that can be used to calculate effect sizes and confidence intervals, and applies these methods in a Monte Carlo simulation. It was found that under most conditions the method of effect size and confidence interval calculation was not relevant