Before entering into a discussion of specific research design techniques, it is important to insert a preliminary discussion of several factors that overshadow all research design issues in case study work. These include evidence-gathering techniques, the formulation of a hypothesis, degrees of falsifiability, the tension between particularizing and generalizing objectives in a case study, the identification of a population that the case study purports to represent, and the importance of cross-level research. Although these six issues affect all empirical work in the social sciences, they are particularly confusing in the context of case study work, and consequently merit our close attention.

The Evidence

The case study, I argued in Chapter Two, should not be defined by a distinctive method of data collection but rather by the goals of the research relative to the scope of the research terrain. Evidence for a case study may be drawn from an existing dataset or set of texts or may be the product of original research by the investigator. Written sources may be primary or secondary. Evidence may be quantitative, qualitative, or a mixture of both – as when qualitative observations are coded numerically so as to create a quantitative variable. Evidence may be drawn from experiments (discussed in Chapter Six), from “ethnographic” field research, from unstructured interviews, or from highly structured surveys.