In the previous chapters we have looked at ways to compare the mean of a variable between two populations. What would happen if we had more than two populations? We could carry out multiple -tests, e.g. between group A and group B, between group A and group C, between group A and group D, between group B and group C, and so on. Alternatively we could carry out a one-way ANalysis Of VAriance (or ANOVA) which, despite its name, is actually a test for differences between group means. We will start by looking at issues which arise from carrying out multiple pairs of -tests.