ABSTRACT
In sections of Chapter 2, we treated the one-way experimental layout, that is, the completely randomized design (CRD), which involved a single factor set at k levels, or the comparison of means of k groups or k populations. Next, in this chapter, we consider experiments in which the effects of levels of two factors on a response variable are studied. In such studies, resources are usually available so that the designed experiment can be replicated. The data from the experiment are presented in a two-way layout, which involves two factors, each set at a number of levels with replications in every cell, where the cells are determined by the combinations of levels of the factors. Equal or unequal number of measurements can be made in each cell. In the following Section 3.1, we consider the two-factor factorial experiment in its simplest form, with equal number of observations per cell. The two-factor factorial experiment is the simplest form of a crossed design; a designed experiment in which replicates involving all the combinations of levels of all the factors are investigated in at least two replicates is called a full factorial experiment. Factors arranged in a factorial experiment are said to be crossed.
