Details of Approaches to Synthesis a Methodological Appendix to the Paper: Systematically Reviewing Qualitative and Quantitative Evidence to Inform Management and Policy Making in the Health Field

Introduction In the paper with which this appendix is linked we have identified four basic approaches to evidence review: narrative approaches (which may include research and non-research based evidence both qualitative and quantitative and typically deal with the findings of included studies in their own terms rather than transforming one form of 'data' into another); qualitative (which convert all available evidence into qualitative form using techniques such as 'meta-ethnography' and 'qualitative cross-case analysis'), quantitative (which convert all evidence into quantitative form using techniques such as 'quantitative case survey' or 'content analysis') and Bayesian meta-analysis and decision analysis (which can convert qualitative evidence such as preferences about different outcomes into quantitative form or 'weights' to use in quantitative synthesis). We recognise that the boundaries between these four 'types' of approaches is somewhat permeable: some approaches we describe as qualitative are essentially narrative in form but this typology provides a heuristic device to help us organise the material. In this appendix we provide some more detail of the approaches discussed in the paper and reference to more technical discussions where appropriate. There is no clearly delineated body of knowledge describing particular narrative approaches to evidence synthesis and substantive discussion of questions of rigour and reliability in relation to these approaches is not readily available. Various terms are used, including 'narrative review', and more recently, 'narrative synthesis' and 'realist synthesis'. These can mean different things to different writers In broad terms, narrative approaches summarise , compare, explain and interpret evidence of all types relevant to a particular question. In the past, these approaches tended to lack transparency and to summarise findings of included studies rather than attempting a synthesis. Typically, however, even more recent approaches do tend to deal with the findings and interpretations from published studies in their own terms, without any attempt to transform them for analytical purposes. Dixon-Woods and colleagues 1 argue that narrative approaches are very flexible, allowing for different types of evidence – both qualitative and quantitative – to be reviewed, though not necessarily allowing full integration. This flexibility and ease of handling of a very wide range of evidence means that such approaches are likely to remain an important tool for policy and management-relevant reviews. Narrative approaches also allow the development and testing of theories and explanations that attempt to account for all the published findings relevant to a question. What are they? The term 'narrative review' …