Repeated Measures ANOVA (Definition)

Repeated Measures ANOVA

Repeated measures ANOVA is

 

1. the extension of the dependent t-test

2. the equivalent of the one-way ANOVA, but for related, not independent groups. 

3. a within-subjects ANOVA or

4. a ANOVA for correlated samples.

5. a test to detect any overall differences between related means.

 

The dependent variable needs to be continuous (interval or ratio) and the independent variable categorical (either nominal or ordinal).

When to use a Repeated Measures ANOVA (Two Types)

We can analyze data using a repeated measures ANOVA for two types of study design.

Studies that investigate either

(1) changes in mean scores over three or more time points

(2) differences in mean scores under three or more different conditions.

 

The important point with these two study designs is that the same people are being measured more than once on the same dependent variable (i.e., why it is called repeated measures).

In repeated measures ANOVA, the independent variable has categories called levels or related groups.

Where measurements are repeated over time, such as when measuring changes in skill levels due to an exercise-training programme, the independent variable is time. Each level (or related group) is a specific time point. Hence, for the exercise-training study, there would be three time points and each time-point is a level of the independent variable (a schematic of a time-course repeated measures design is shown below)