ABSTRACT
In this chapter we consider how to go about choosing a design for the problem we want to investigate. There are advantages and disadvantages to any design, and whatever we are investigating, we want to find a design that will address the question as directly as possible and that will have few disadvantages. We have to consider any factors that limit our choice of design, and if several types of design could be suitable, we need to be sure we know the advantages and disadvantages of each. In this introductory section, we briefly describe the classes of designs. Later sections will give the conditions in which each design may be used.
