Analysis of variance (ANOVA) is the multigroup generalization of the t test (Chapter 5). Like the t test, ANOVA assumes that samples are randomly drawn from normally distributed populations with the same standard deviations. If differences between the observed means of the samples are larger than one would expect from the underlying population variability, estimated by the standard deviations within the samples, you can conclude that at least one of the samples has a different mean than the others.
provides classes for both one-way
(or one-factor) and two-way
This chapter describes the analysis of variance classes.