NUMBAT OER - Open Educational Resources

Since this is a nonparametric test, a box plot is an appropriate presentation of the data. A box plot is constructed for each sample in order to compare them.

Two box plot example
Example of two box plots used to compare samples, in this case bone densities in men and women

The different elements of the box plot are indicated here:

Single box plot example
Example of a single box plot output by SPSS, with extreme values and outliers indicated separately

An error plot may also be appropriate for this sort of data, and is used in the example report. It shows the mean and variance of the samples being compared and, like the box plot, is a clear way of demonstrating the degree of overlap between samples.

Error plot examples
Examples of error plots comparing two samples with differing degrees of overlap