Sample size for qualitative research
Open accessAbstract
Purpose: Qualitative researchers have been criticised for not justifying sample size decisions in their research. This short paper addresses the issue of which sample sizes are appropriate and valid within different approaches to qualitative research. Design/methodology/approach: The sparse literature on sample sizes in qualitative research is reviewed and discussed. This examination is informed by the personal experience of the author in terms of assessing, as an editor, reviewer comments as they relate to sample size in qualitative research. Also, the discussion is informed by the author’s own experience of undertaking commercial and academic qualitative research over the last 31 years. Findings: In qualitative research, the determination of sample size is contextual and partially dependent upon the scientific paradigm under which investigation is taking place. For example, qualitative research which is oriented towards positivism, will require larger samples than in-depth qualitative research does, so that a representative picture of the whole population under review can be gained. Nonetheless, the paper also concludes that sample sizes involving one single case can be highly informative and meaningful as demonstrated in examples from management and medical research. Unique examples of research using a single sample or case but involving new areas or findings that are potentially highly relevant, can be worthy of publication. Theoretical saturation can also be useful as a guide in designing qualitative research, with practical research illustrating that samples of 12 may be cases where data saturation occurs among a relatively homogeneous population. Practical implications: Sample sizes as low as one can be justified. Researchers and reviewers may find the discussion in this paper to be a useful guide to determining and critiquing sample size in qualitative research. Originality/value: Sample size in qualitative research is always mentioned by reviewers of qualitative papers but discussion tends to be simplistic and relatively uninformed. The current paper draws attention to how sample sizes, at both ends of the size continuum, can be justified by researchers. This will also aid reviewers in their making of comments about the appropriateness of sample sizes in qualitative research.
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Use of saturation to indicate ability to extrapolate or generalisation could indicate confusion about the meaning and purpose of saturation.
“The use of saturation in these two cases could perhaps indicate a degree of confusion in some studies about the meaning of saturation and its purpose”
From Saturation in qualitative research: exploring its conceptualization and operationalization (2018) · cites this paper as Boddy (2016)
A sample size of 10 interviews per community would provide enough information and variation in data within the target population.
“We determined that a sample size of 10 interviews per community would provide enough information and variation in data within the target population [27].”
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“Invitations continued until 12 interviews were conducted, which was deemed sufficient given the objectives and the exploratory nature of this study, and this is consistent with prior recommendations [53,54].”
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- Authors
- Boddy, C. R.
- Affiliations
- Middlesex University London (GB)
- Corresponding author
- Boddy, Clive Roland
- ORCID
- Boddy, Clive Roland
- Venue
- Qualitative Market Research: An International Journal
- Publisher
- Emerald
- Published
- 2016-09-12
- Volume
- 19
- Issue
- 4
- Pages
- 426-432
- ISSN
- 1352-2752 (ISSN-L)
- OpenAlex
- W2523074512
- Cited by
- 1,669
- References
- 19
- Citations by year
- 2026: 168 · 2025: 259 · 2024: 293 · 2023: 255 · 2022: 229 · 2021: 196 · 2020: 127 · 2019: 60 · 2018: 57 · 2017: 11 · 2016: 4 · 2015: 7
- FWCI
- 195.29
- Type
- journal article
- Language
- en
- Open access
- green
- figshare.com
- Licence
- Locations
- Qualitative Market Research An International Journal (publishedVersion)
- eCite Digital Repository (University of Tasmania) (submittedVersion)
- Figshare (submittedVersion, cc-by)
- Topics
- Social Sciences › Education › Qualitative Research Methods and Applications
- Social Sciences › Sociology and Political Science › Qualitative Research Methods and Ethics
- Social Sciences › Decision Sciences › Management Science and Operations Research › Business Strategies and Management Research
- Keywords
- sample size, qualitative research, data saturation, theoretical saturation, single subject research, positivism, research design, peer review
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