Purposive sampling in a qualitative evidence synthesis: a worked example from a synthesis on parental perceptions of vaccination communication
Purposive sampling in a qualitative evidence synthesis: a worked example from a synthesis on parental perceptions of vaccination communication
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DOI：
10.1186/s12874-019-0665-4
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发表时间：
2019-01-31
影响因子：
4
通讯作者：
Lewin, Simon
中科院分区：
文献类型：
--
作者：
Ames, Heather;Glenton, Claire;Lewin, Simon
背景在定性证据合成中，由于大量研究而产生的过多数据可能会削弱我们进行彻底分析的能力。有目的地对初步研究进行抽样，以便纳入合成，是实现可管理的数据量的一种方式。这篇文章的目的是描述疫苗接种传播定性证据合成的抽样框架的发展和应用。方法我们开发并应用了一个三步框架来从符合纳入条件的研究中抽样研究。我们的目标是对来自一系列背景、与审查尽可能相关、拥有丰富数据的研究进行优先排序。我们从每个研究中提取了关于国家和研究背景、疫苗、数据丰富度和研究目标的信息，并应用了以下抽样框架：在低收入和中等收入环境中进行的研究在数据丰富度的5分制上得分4分或更高的研究研究目标与我们的综合目标非常匹配的研究结果我们评估了79项研究符合纳入综合研究的条件，并对其中38项进行了抽样。首先，我们对来自低收入和中等收入国家的所有九项研究进行了抽样。这些研究得出的发现数量最少。然后，我们对另外24项数据丰富性得分较高的研究进行了抽样。这些研究促成了更多的发现。最后，我们对另外五项与我们的合成目标最接近的研究进行了抽样。这些有助于大量的发现。结论我们的目的抽样方法有助于确保我们纳入的研究代表了广泛的地理分布、丰富的数据和与我们的综合目标非常相似的重点。我们有可能忽视了不符合我们抽样标准的初步研究，但这些研究本来可以对综合做出贡献。例如，关于移徙和获得保健服务的两项研究不符合抽样标准，但可能有助于加强至少一个结论。我们需要各种方法来交叉检查未被充分代表的主题。
BackgroundIn a qualitative evidence synthesis, too much data due to a large number of studies can undermine our ability to perform a thorough analysis. Purposive sampling of primary studies for inclusion in the synthesis is one way of achieving a manageable amount of data. The objective of this article is to describe the development and application of a sampling framework for a qualitative evidence synthesis on vaccination communication.MethodsWe developed and applied a three-step framework to sample studies from among those eligible for inclusion in our synthesis. We aimed to prioritise studies that were from a range of settings, were as relevant as possible to the review, and had rich data. We extracted information from each study about country and study setting, vaccine, data richness, and study objectives and applied the following sampling framework:Studies conducted in low and middle income settingsStudies scoring four or more on a 5-point scale of data richnessStudies where the study objectives closely matched our synthesis objectivesResultsWe assessed 79 studies as eligible for inclusion in the synthesis and sampled 38 of these. First, we sampled all nine studies that were from low and middle-income countries. These studies contributed to the least number of findings. We then sampled an additional 24 studies that scored high for data richness. These studies contributed to a larger number of findings. Finally, we sampled an additional five studies that most closely matched our synthesis objectives. These contributed to a large number of findings.ConclusionsOur approach to purposive sampling helped ensure that we included studies representing a wide geographic spread, rich data and a focus that closely resembled our synthesis objective. It is possible that we may have overlooked primary studies that did not meet our sampling criteria but would have contributed to the synthesis. For example, two studies on migration and access to health services did not meet the sampling criteria but might have contributed to strengthening at least one finding. We need methods to cross-check for under-represented themes.