Analysis of variance (a.k.a. ANOVA) is used to compare the means of more than 2 groups. Unsurprisingly, the way ANOVA works is by comparing variances (hence the name Analysis of Variance…). Variables must be categorical, and will often be called factors. There are several designs for ANOVA, depending on the number of variables to be compared and on whether samples are measured several times during the course of an experiment. In this chapter, we’ll talk about:

one-way ANOVA (1 single variable/factor with more than 2 levels),

factorial design alias two-way ANOVA, three-way ANOVA, multi-way ANOVA (2 or more factors with 2 or more levels each),

repeated measures ANOVA (individuals of the sample are tested/measured several times during the course of an experiment).