A simple method to assess and report thematic saturation in qualitative research

Abstract

Data saturation is the most commonly employed concept for estimating sample sizes in qualitative research. Over the past 20 years, scholars using both empirical research and mathematical/statistical models have made significant contributions to the question: How many qualitative interviews are enough? This body of work has advanced the evidence base for sample size estimation in qualitative inquiry during the design phase of a study, prior to data collection, but it does not provide qualitative researchers with a simple and reliable way to determine the adequacy of sample sizes during and/or after data collection. Using the principle of saturation as a foundation, we describe and validate a simple-to-apply method for assessing and reporting on saturation in the context of inductive thematic analyses. Following a review of the empirical research on data saturation and sample size estimation in qualitative research, we propose an alternative way to evaluate saturation that overcomes the shortcomings and challenges associated with existing methods identified in our review. Our approach includes three primary elements in its calculation and assessment: Base Size, Run Length, and New Information Threshold. We additionally propose a more flexible approach to reporting saturation. To validate our method, we use a bootstrapping technique on three existing thematically coded qualitative datasets generated from indepth interviews. Results from this analysis indicate the method we propose to assess and report on saturation is feasible and congruent with findings from earlier studies.

Valuing All Voices: refining a trauma-informed, intersectional and critical reflexive framework for patient engagement in health research using a qualitative descriptive approach

“…PR conducted a full thematic analysis and kept a reflexive practice journal throughout, to ensure bracketing (attempting to mitigate preconceptions about the work) and maintain audit trails [42]. Retrospective analysis was used to assess data saturation [38], wherein a 'base' set of interviews (i.e. the first six) are assessed for how much new information they produce.…”

“…However, as recommended by community organizations, to ensure participant comfort, safety, and confidentiality when discussing sensitive issues and experiences, individual interviews were subsequently selected as the method of data collection with immigrant participants and those with lived experience of a mental health condition. Approximately eight participants were invited to group or individual interviews for each group, as is reported to be sufficient to achieve data saturation [37,38]. Interviews were preceded by introductions.…”

The Curated Food System: A Limiting Aspirational Vision of What Constitutes “Good” Food

“…Data from scholarly and grey literature, websites, interviews with food system experts and advocates, and an email exchange between food system experts was used to identify discourses and passages that exemplified the discourses. In qualitative research, with respect to sample size, it is often sufficient to use a sample of just a few texts, documents, or interview transcripts because the focus of interest is on repetition until the saturation point is reached [ 18 , 19 ]. Understanding the “how” and “why” is elevated in qualitative research over “how many” [ 20 , 21 ].…”

Caring for older patients with advanced chronic kidney disease and considering their needs: a qualitative study

“…After reviewing all transcripts, themes were generally consistent across varied perspectives within the sample [22]. We determined that we had reached thematic saturation at this point [14,22,23]. Coding discrepancies were resolved via consensus.…”