Theoretical sampling

Abstract

It is important to understand that in qualitative research, 'size' does not mean 'significance'. Here is a long-standing issue that many qualitative researchers face, especially those whose research environments are strongly quantitative: how to deal with qualitative sampling? Achieving significant data leads researchers to sample participants according to their knowledge and experience regarding a specific phenomenon: commonly described as 'purposive'. Purposive or purposeful sampling can be defined a priori, that is to say, before the beginning of data collection process (Charmaz 1990). Purposive sampling and its underlying decision-making process are, usually, driven by 'tradition' and 'best practices'. For example, Mason (2010) gathered sampling indications from qualitative researchers: Morse (1994) suggests conducting 30–50 interviews for ethnography, ethnoscience and grounded theory; for a phenomenological study, she indicates at least six interviews/participants. Creswell (1998) conveys 20–30 interviews for grounded theory and from five up to 25 interviews for phenomenology. At any rate, the issue is still there, as Mason (2010) stresses: 'While these numbers are offered as guidance, the authors do not tend to present empirical arguments as to why these numbers and not others for example. Also the issue of why some authors feel that certain methodological approaches call for more participants compared to others, is also not explored in any detail' (Mason 2010, p. 11).…