In this chapter, we will be encountering some issues that are fundamental to an appreciation of how people (or whatever is the unit of analysis) should be selected for inclusion in a study and of how it is possible to generalize to the population from which people are selected. These two related issues are concerned with sampling and the statistical significance of results. In examining sampling we will be looking at the procedures for selecting people so that they are representative of the population from which they are selected. The topic of statistical significance raises the issue of how confident we can be that findings relating to a sample of individuals will also be found in the population from which the sample was selected.