Where can I find a good effect size calculator?

When people learn about effect sizes, one of the first things they ask is “what software do I need to calculate effect sizes?”

Many effect size indexes can be calculated on the back of an envelope or using nothing more than a Spreadsheet.

Other effect size indexes are generated automatically by statistical programs such as SPSS or STATA.

Still, for those of you who want something flashy, a set of seven easy to use calculators can be found on the Resources page (or just click here to be taken straight to the effect size calculators).