Analysis of Variance (ANOVA)

General resources

A tutorial geared towards psychology research.

One Way

Two Way

Repeated Measures

In R, repeated measures ANOVA needs to be fit using aov, so that a multi-stratum error term can be a part of the model (lm does not support this). lme (from the nlme library'') can also be used for this purpose, specifying the error terms in the random= argument.

Post-hoc analysis

If multiple treatments need to be compared after the experiment, a couple types of post-hoc analyses can be used to test whether the means of the treatments are significantly different. These are the Tukey range test (also known as Tukey-Kramer, or Tukey HSD) and Scheffe's method.