Choosing a suitable sample size in qualitative research is an area of conceptual debate and practical uncertainty. That sample size principles, guidelines and tools have been developed to enable researchers to set, and justify the acceptability of, their sample size is an indication that the issue constitutes an important marker of the quality of qualitative research. Nevertheless, research shows that sample size sufficiency reporting is often poor, if not absent, across a range of disciplinary fields. A systematic analysis of single-interview-per-participant designs within three health-related journals from the disciplines of psychology, sociology and medicine, over a 15-year period, was conducted to examine whether and how sample sizes were justified and how sample size was characterised and discussed by authors. Data pertinent to sample size were extracted and analysed using qualitative and quantitative analytic techniques. Our findings demonstrate that provision of sample size justifications in qualitative health research is limited; is not contingent on the number of interviews; and relates to the journal of publication. Defence of sample size was most frequently supported across all three journals with reference to the principle of saturation and to pragmatic considerations. Qualitative sample sizes were predominantly – and often without justification – characterised as insufficient (i.e., ‘small’) and discussed in the context of study limitations. Sample size insufficiency was seen to threaten the validity and generalizability of studies’ results, with the latter being frequently conceived in nomothetic terms. We recommend, firstly, that qualitative health researchers be more transparent about evaluations of their sample size sufficiency, situating these within broader and more encompassing assessments of data adequacy. Secondly, we invite researchers critically to consider how saturation parameters found in prior methodological studies and sample size community norms might best inform, and apply to, their own project and encourage that data adequacy is best appraised with reference to features that are intrinsic to the study at hand. Finally, those reviewing papers have a vital role in supporting and encouraging transparent study-specific reporting.

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Characterising and justifying sample size sufficiency in interview-based studies: systematic analysis of qualitative health research over a 15-year period

Generalisation in relation to qualitative research has rarely been discussed in-depth in sport and exercise psychology, the sociology of sport, sport coaching, or sport management journals. Often t...

Generalizability in qualitative research: misunderstandings, opportunities and recommendations for the sport and exercise sciences

Qualitative methods are a valuable tool in implementation research because they help to answer complex questions such as how and why efforts to implement best practices may succeed or fail, and how patients and providers experience and make decisions in care. This article orients the novice implementation scientist to fundamentals of qualitative methods and their application in implementation research, describing: 1) implementation-related questions that can be addressed by qualitative methods; 2) qualitative methods commonly used in implementation research; 3) basic sampling and data collection procedures; and 4) recommended practices for data analysis and ensuring rigor. To illustrate qualitative methods decision-making, a case example is provided of a study examining implementation of a primary care-based collaborative care management model for women Veterans with anxiety, depression, and PTSD.

Qualitative methods in implementation research: An introduction.

In the mid-1980s, Heckhausen and Gollwitzer set out to analyze how people control their actions (see Heckhausen, Gollwitzer, & Weinert, 1987). They quickly realized that breaking action control down into different phases greatly benefited its understanding. Heckhausen and Gollwitzer’s analysis was heavily influenced by the work of Kurt Lewin (e.g., Lewin et al., 1944), for whom there was never any doubt that motivational phenomena can only be properly understood and analyzed from an action perspective that distinguishes the processes of goal setting from those of goal striving, an insight that went unheeded for several decades. Accordingly, Heckhausen and Gollwitzer (1987) proposed the “Rubicon”model of action phases, which describes the course of action as a temporal, linear path starting with a person’s wishes or desires and ending with the evaluation of the action outcomes achieved. The model was designed to raise and help answer the following questions: How do people select their goals? How do they plan the execution of goal striving? How do they enact these plans? Moreover, how do they evaluate their accomplishments? According to the Rubicon model, a course of action involves a phase of deliberating the desirability and feasibility of one’s wishes at the outset in order to arrive at a binding decision regarding which of them one wants to pursue as a goal (pre-decisional phase), a phase of planning concrete strategies for achieving this goal Practical Summary

Changing Behavior Using the Model of Action Phases

The Handbook of Behaviour Change

Seventy six senior academics from 11 countries invite The BMJ ’s editors to reconsider their policy of rejecting qualitative research on the grounds of low priority. They challenge the journal to develop a proactive, scholarly, and pluralist approach to research that aligns with its stated mission

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Stefania Rodella

Papers

An open letter to The BMJ editors on qualitative research