Variations of mixed methods reviews approaches: A case study

Conducting mixed methods reviews is challenging. The aim of this article is to describe a range of rationales for and approaches to mixed methods reviews, with a particular focus on one research group. A case study was conducted to describe the mixed methods review process used at the Department of Health and Social Care Reviews Facility in England. The case study used document analysis. A total of 30 mixed methods reviews were identified and analyzed. The analysis revealed five key dimensions on which the reviews varied: review questions and purposes of the mixed methods questions, types of evidence and sources, reasons for using a mixed methods approach, synthesis methods and designs, and integration strategies. The questions in the included reviews addressed stakeholders' views, and intervention processes and/or intervention effectiveness. The mixed methods questions addressed four different purposes: comparing findings, identifying critical intervention features, quantifying effects, and making recommendations. Five main sources of evidence were used: formal evidence from primary studies, informal evidence, policy documents, systematic reviews, and work with stakeholders. Twelve reasons for conducting mixed methods reviews were identified: completeness, contextual understanding, credibility, different research questions, diversity of views, enhancement, explanation, process, triangulation, utility, development of a framework, and identification of promising interventions. Each review employed one or several integration strategies for comparing findings, connecting phases and/or assimilating data. It is hoped that the information garnered from this study will provide useful insights into mixed method review diversity and trigger new ideas for conducting this type of review.