Characterising and justifying sample size sufficiency in interview-based studies: systematic analysis of qualitative health research over a 15-year period.
Characterising and justifying sample size sufficiency in interview-based studies: systematic analysis of qualitative health research over a 15-year period.
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DOI：
10.1186/s12874-018-0594-7
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发表时间：
2018-11-21
影响因子：
4
通讯作者：
Young T
中科院分区：
文献类型：
--
作者：
Vasileiou K;Barnett J;Thorpe S;Young T
在定性研究中，选择合适的样本量是一个概念争论和实践不确定性的领域。制定样本量原则、准则和工具，使研究人员能够确定样本量，并证明其可接受性，这表明这一问题是定性研究质量的一个重要标志。然而，研究表明，在一系列学科领域，样本量充分性报告往往很差，如果不是不存在的话。在心理学，社会学和医学学科的三个健康相关的期刊，在15年的时间内，进行了系统的分析，以检查是否和如何样本量是合理的，以及如何样本量的特点和讨论的作者。提取与样本量有关的数据，并使用定性和定量分析技术进行分析。我们的研究结果表明，提供定性健康研究的样本量的理由是有限的，是不依赖于采访的数量，并涉及到出版的杂志。在所有三种期刊中，样本量的辩护最常得到饱和原则和务实考虑的支持。定性样本量主要--而且往往没有理由--被描述为不足（即，“小”），并在研究限制的背景下进行讨论。样本量不足被认为威胁到研究结果的有效性和普遍性，后者经常被认为是规则性的。我们建议，首先，定性的健康研究人员更透明的评估他们的样本量充足，这些位于更广泛和更全面的评估数据充分性。其次，我们邀请研究人员批判性地考虑如何在以前的方法学研究和样本量社区规范中发现的饱和参数可能最好地通知，并适用于他们自己的项目，并鼓励数据充分性是最好的评估参考的特征是内在的研究在手。最后，这些审查文件在支持和鼓励透明的研究报告方面发挥着至关重要的作用。本文的在线版本（10.1186/s12874 - 018 - 0594 - 7）包含补充材料，可供授权用户使用。
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. The online version of this article (10.1186/s12874-018-0594-7) contains supplementary material, which is available to authorized users.