Measure of the Effect was developed to calculate effect sizes and their confidence intervals. First, a range of effect sizes will be included, such as Cohen’s d, omega, eta, r/R, phi, f, and odds-ratios. In cases where formulas were not ubiquitously agreed upon, both versions of calculations are provided. For example, Cohen’s d for dependent t-tests is traditionally calculated by divided the mean difference between time measurements by the standard deviation of the difference scores. However, as Cumming (2012) outlines, effect sizes can be artificially inflated with small difference scores, and therefore recommends dividing the mean differences by the average standard deviation of the two time measurements. Formulae are provided in the user’s guide and directly on the program, so users will know and can cite how they calculated their effect sizes. This information will also allow the users to understand their effect size in terms of its dimension, index, and value, which follows well with recent work (Kelley & Preacher, 2012).

You can download the JAVA version while we work on the online version here.

Check out the long abstract on why effect size programs are necessary here.