ABSTRACT
This chapter generalizes comparing a response variable across two groups from the previous chapter to a grouping variable defined by an arbitrary number of groups, though usually from two to about six or seven groups. Accomplish the statistical comparison of several groups with the analysis of variance or ANOVA, performed with the lessR function of the same name, ANOVA(). The comparison of the means across several groups is called one-way analysis of variance. When the groups are composed of matched data values across the groups, the analysis is the one-way randomized block ANOVA. This chapter presents both techniques, along with their nonparametric alternatives.
