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Below you will find descriptions and links to 5 free statistics calculators for computing statistical effect sizes.

If you like, you may also use the search page to help you find what you need.

This calculator will tell you the (two-tailed) effect size for a Student t-test (i.e., Cohen's d), given the mean and standard deviation for two independent samples of equal size.

This calculator will tell you the effect size for a hierarchical multiple regression study (Cohen's f^{2}), given an R^{2} value for a set of independent variables A, and an R^{2} value for the sum of A and another set of independent variables B. The value returned by the calculator is the effect size attributable to the addition of set B to the model.

This calculator will tell you the effect size for a multiple regression study (i.e., Cohen's f^{2}), given a value of R^{2}.

This calculator will compute the 99%, 95%, and 90% confidence intervals for the f^{2} effect size associated with a multiple regression study, given the f^{2} value, the number of predictors in the model, and the total sample size.

This calculator will compute an R^{2} value for a multiple regression model, given Cohen's f^{2} effect size for the model.