Determining Adequate Sample Sizes for Qualitative Data Analysis Methods: A Review
"Balancing Depth and Breadth: Insights into Sampling Strategies for Robust Qualitative Analysis"
Introduction
Qualitative research employs various data analysis methods, each with its own considerations for determining adequate sample sizes. This paper reviews the current literature on sample size guidelines for 10 types of qualitative analysis, including five types of saturation and five common methods, to provide researchers with a comprehensive understanding of the topic.
Methods
The review covers five types of saturation: theme, meaning, metatheme, salience, and theoretical saturation. Additionally, it examines five common qualitative analysis methods: reflexive thematic analysis, ethnography, schema analysis, classical content analysis, and qualitative content analysis. The authors synthesize findings from relevant studies to present sample size recommendations for each approach.
Results For the saturation types, the review found the following sample size guidelines:
Theme saturation: 9 interviews or 4 focus groups (Guest et al., 2006, 2017; Hennink & Kaiser, 2022)
Meaning saturation: 24 interviews or 8 focus groups (Hennink et al., 2017, 2019; Hennink & Kaiser, 2022)
Metatheme saturation: 20-40 interviews per site (Hagaman & Wutich, 2017)
Saturation in salience: 10 exhaustive free lists (Weller et al., 2018)
Theoretical saturation: 20-30+ interviews (Mason, 2010; Thomson, 2011)
For the five qualitative analysis methods, the findings were as follows:
Reflexive thematic analysis: No clear guidelines (Braun & Clarke, 2022a)
Ethnography: 50-81 data documents or 20-30 interviews (DiStefano & Yang, 2024; Weller, 2007; Weller & Romney, 1988)
Schema analysis: No explicit guidelines (D'Andrade, 2005; Dengah et al., 2021)
Classical content analysis: Statistical power analysis (Krippendorff, 2013; Weller, 2015)
Qualitative content analysis: Information power approach (Malterud et al., 2016, 2021)
Data has been sourced from the study Wutich, A., Beresford, M., & Bernard, H. R. (2024). Sample sizes for 10 types of qualitative data analysis: An integrative review, empirical guidance, and next steps. International Journal of Qualitative Methods. https://doi.org/10.1177/16094069241296206
Discussion
The review highlights an over-reliance on theme saturation in the qualitative research field and emphasizes the need for more research on other saturation types. The authors suggest that meta-analyses and empirical studies on factors affecting saturation, such as research topic, sampling, and data type, are crucial next steps to provide more comprehensive sample size guidance.
Conclusion
This review offers researchers a consolidated resource for determining adequate sample sizes across various qualitative data analysis methods. By understanding the current guidelines and identifying areas for further research, qualitative researchers can make informed decisions when designing their studies and contribute to the development of more robust sample size recommendations.
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