How to: Repeated measures one-way ANOVA

Repeated measures one-way ANOVA compares the means of three or more matched groups.

1. Enter data

From the Welcome (or New Table and graph) dialog, choose the Column tab and a before-after graph.

If you aren't ready to enter your own data, choose to use sample data, and choose: One-way ANOVA - Repeated-measures.

Enter the data for each group into a separate column. Enter data for each subject (or each matched set of results) on a separate row. Optionally, identify the subjects with row titles. If you leave any values blank, Prism will not be able to perform repeated measures ANOVA.

2. Choose one-way ANOVA

1.	From the data table, click on the toolbar.

3. Choose a multiple comparison test

If you are comparing three or more groups, you may pick a post test to compare pairs of group means. Choosing an appropriate multiple comparison test is not straightforward, and different statistics texts make different recommendations. With repeated-measures data, the test for linear trend often is most useful (assuming that the columns are arranged in a natural order e.g. dose or time).

The other post tests are less helpful with repeated-measures data, but you can choose them if you want.

4. Review the results and view the graph

ANOVA investigates the likelihood that the difference among the means could have been caused by chance. The most important results are the P value and the results of post tests.

Before accepting the results, review the analysis checklist.