In the fields of health, psychology, and education, many important outcomes are expressed in shades of gray as opposed to black and white. These shades of gray (e.g., mental and physical suffering and disability) are frequently reported in terms of “effect size”, which, despite its growing use, is not a particularly intuitive expression. The Effect Size Illustrator (ESI) is an interactive tool that helps with the practical interpretation of effect sizes. It can be used when two or more groups are being compared using continuous measures (e.g., weight, exercise duration, pain). You can get started right away by clicking “Effect Size Illustrator”. You’ll quickly realize that customizing your calculations and illustrations is straightforward. Refer to the menu to read more about the ESI and about effect size.