Matched groups to compare 3 or more factor levels

The idea of using matched pairs of experimental units to give more accurate comparisons of two factor levels can be generalised to experiments with 3 or more factor levels.

The experimental units can be grouped into collections of similar units whose size equals the number of factor levels. The different factor levels are randomly allocated to the units within each such matched group.

Again, this type of experiment results in more accurate estimates of the differences between the factor levels than a completely randomised experiment.