effectsize.science

An interactive tool for visualizing effect sizes

This tool allows you to see the effect size (d) and percent overlap for any comparison between two samples. Enter the mean and standard deviation below for each group. If you have the standard error instead of the standard deviation, check the box to enter it and the sample size (n).

Sample 1 Mean
Sample 1 SD
Sample 2 Mean
Sample 2 SD
Use Standard Error

d = 1.91 (large)

overlap = 34%

Export CSV

Sample 1

3% of the values from sample 1 are below the average for sample 2

Sample 2

2% of the values from sample 2 are above the average for sample 1

Sample 1 Color
Sample 2 Color

This tool assumes both distributions are normal. Effect size is based on Cohen’s d. Overlap is based on Weitzman’s ∆. This site is brought to you by the developers of SexDifference.org. The source code is available at GitHub under AGPLv3. If you use this tool to prepare a publication, please cite: Maney DL. 2016 Perils and pitfalls of reporting sex differences. Phil. Trans. R. Soc. B 371: 20150119. https://dx.doi.org/10.1098/rstb.2015.0119