ABSTRACT
Throughout the biosciences, questions of comparison are very common, but the simple one- and two-sample comparisons merely represent the tip of a very large iceberg. The terms, factor and level, are the keys to distinguish between two broad types of multiple comparison. This chapter presents two questions involving multiple comparisons into two broad groups: those involving a single factor, and those where one focuses on more than one experimental variable. This chapter describes how one can evaluate the effects of several factors simultaneously. These designs are often described as factorial designs. The chapter outlines how blocking or repeated measures can be incorporated into such designs. The detail of the effects of the interaction between factors and the factors acting individually are determined using Tukey tests. The chapter also outlines the principal methods that are used in biological investigations and also explain why and how one can use them.
