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

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.