Selecting a sample

Sampling is somewhat underemphasized compared to how data are collected and analyzed in empirical qualitative research. Yet qualitative research in particular needs transparent and comprehensible procedures about how to select units of analysis. In this chapter, we will address this issue in three major steps.
First, we will start with discussing some basic questions. Respecting the claim that social research has to yield results that go beyond a single case, we will outline how different research purposes such as principles of generalization – which are presented and discussed in more detail in an extra chapter (see Maxwell, Chapter 20) – constitute a framework for sampling that is shaped by various contextual factors. Depending on the respective positions in these areas, sampling has to meet different criteria.
Second, we will outline how major approaches to qualitative research deal with sampling questions: ethnography (see Buscatto, Chapter 28, this Handbook), phenomenology (see Eberle, Chapter 7), grounded theory (see Thornberg and Keane, Chapter 27), critical discourse analysis (see Kutter and Masson, Chapter 62), and case study research (see Tight, Chapter 24). What is their general understanding of sampling? Do they suggest specific criteria and procedures regarding how to sample? Which definitions of sampling units do they apply, if any? Which criteria do they suggest to use in order to decide about sample size and saturation? Previous research indicates a remarkable heterogeneity and no unanimous answer to these questions.
Third, we will suggest how to design sampling: which questions have to be asked before starting to sample? Which methods can be applied to select units? Though we assume there are only two basic strategies – convenience and purposeful sampling (see Patton Chapter 70) – we will discuss how different purposes result in different sampling techniques.