Sampling Designs in Qualitative Research: Making the Sampling Process More Public
Onwuegbuzie, Anthony J., Leech, Nancy L., The Qualitative Report
The purpose of this paper is to provide a typology of sampling designs for qualitative researchers. We introduce the following sampling strategies: (a) parallel sampling designs, which represent a body of sampling strategies that facilitate credible comparisons of two or more different subgroups that are extracted from the same levels of study; (b) nested sampling designs, which are sampling strategies that facilitate credible comparisons of two or more members of the same subgroup, wherein one or more members of the subgroup represent a sub-sample of the full sample; and (c) multilevel sampling designs, which represent sampling strategies that facilitate credible comparisons of two or more subgroups that are extracted from different levels of study. Key Words: Qualitative Research, Sampling Designs, Random Sampling, Purposive Sampling, and Sample Size
Setting the Scene
According to Denzin and Lincoln (2005), qualitative researchers must confront three crises; representation, legitimation, and praxis. The crisis of representation refers to the difficulty for qualitative researchers in adequately capturing lived experiences. As noted by Denzin and Lincoln,
Such experience, it is argued, is created in the social text written by the researcher. This is the representational crisis. It confronts the inescapable problem of representation, but does so within a framework that makes the direct link between experience and text problematic. (p. 19)
Further, according to Denzin and Lincoln (2005), the crisis of representation asks whether qualitative researchers can use text to represent authentically the experience of the "Other" (p. 21). The crisis of legitimation refers to "a serious rethinking of such terms as validity, generalizability, and reliability, terms already retheorized in postpositivist ..., constructivist-naturalistic ..., feminist ..., interpretive ..., poststructural ..., and critical ... discourses" (Denzin & Lincoln, p. 19) [italics in original]. Finally, the crisis of praxis leads qualitative researchers to ask, "how are qualitative studies to be evaluated in the contemporary, poststructural moment?" (Denzin & Lincoln, pp. 19-20).
The crises of representation, legitimation, and praxis threaten qualitative researchers' ability to extract meaning from their data. As noted by Onwuegbuzie and Leech (2004a),
In particular, lack of representation means that the evaluator has not adequately captured the data. Lack of legitimation means that the extent to which the data have been captured has not been adequately assessed, or that any such assessment has not provided support for legitimation. Thus, the significance of findings in qualitative research is affected by these crises. (p. 778)
In an attempt to address these crises and to prevent "the naturalistic approach ... [from being] tarred with the brush of 'sloppy research'" (Guba, 1981, p. 90), in recent years, there has been increased focus on rigor in qualitative research, where rigor is defined as the goal of making "data and explanatory schemes as public and replicable as possible" (Denzin, 1978, p. 7). More specifically, recent attempts have been made to make the research process more public (cf. Anfara, Brown, & Mangione, 2002). In particular, qualitative methodologists have provided frameworks for making qualitative data analyses more explicit (Anfara et al.; Constas, 1992), so that qualitative studies promote "openness on the grounds of refutability and freedom from bias" (Anfara et al., p. 28).
In contrast, scant discussion has taken place vis-a-vis sampling in qualitative research. Indeed, using the keywords "qualitative research" and "sampling," as well as "qualitative research" and "sample size," a review of the most prominent academic literature databases (e.g., ERIC, PsycINFO) yielded only seven published journal articles (i. …