Defining a sample size before starting a grounded theory project can be challenging, not least because the intention is that once data collection in a grounded theory study has commenced it continues until the theory is saturated, that is, until new data ceases to provide additional insights. There are no agreed upon recommendations for grounded theory sample sizes and, with an emphasis on theoretical saturation, it is impossible to definitively state how many participants will be needed as part of a grounded theory study.
Key grounded theorists have variously suggested that researchers start with a small to moderate sample size which is then adjusted based on the evolving scope of the study and the emerging insights, while recommending that the anticipated number of data collection points should be increased if pursuing a controversial topic or if anticipating provocative findings.
While a definitive sample size remains elusive, a pragmatic approach is needed to satisfy the requirements of research and ethics committees. A common perspective is to become familiar with what sample size is considered standard within a particular discipline, stating that “a minimum of 10 participants” will be recruited or, based on a content analysis of self-defined interview-based grounded theory studies, anticipating “between 10 and 30 interviews”. Whichever approach is selected, the advice is to err towards stating a larger sample size than initially anticipated to avoid having to apply for an amendment to an application should the sample size need to be expanded.
References
Birks, M., & Mills, J. (2023). Grounded theory: a practical guide (3rd ed.). London: SAGE Publications Ltd.
Charmaz, K. (2014). Constructing grounded theory (2nd ed.). London: Sage.
Glaser, B. G., & Strauss, A. L. (1967). The discovery of grounded theory: strategies for qualitative research. New York: Aldine.
Morse, J. M., & Clark, L. (2019). The nuances of grounded theory sampling and the pivotal role of theoretical sampling. In A. Bryant & K. Charmaz (Eds.), The SAGE handbook of current developments in grounded theory (pp. 145-166). London: SAGE Publications Ltd.
Strauss, A. L., & Corbin, J. (2015). Basics of qualitative research: techniques and procedures for developing grounded theory. London: Sage. 2nd ed.
Thomson, S. B. (2011). Sample size and grounded theory. Journal of Administration & Governance, 5(1), 45-52.
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