Synthesis method | Description | Sampling method | Rationale for sampling method |
---|---|---|---|
Critical interpretive synthesis | A method of synthesis that offers a means of systematically producing explanatory theories directly from the data. | (1) Purposive sampling; (2) Theoretical sampling [65] | (1) Purposive sampling of representative cases used to immerse team in area of investigation. (2) Followed up by pursuit of further lines of theoretical inquiry. |
Grounded theory-based approaches | An interpretive approach to synthesis that is modelled on the primary research methods of grounded theory. | Theoretical sampling [34] | Further lines of inquiry and hence routes for searching emerge from ongoing analysis of the data and hence require follow up along lines suggested by theory. |
Meta-aggregation | A structured, process-driven approach to systematic review of qualitative research modelled on the conventional systematic review of quantitative literature as practised by the Cochrane and Campbell Collaboration. | Seeks to identify all relevant studies in order to establish credibility in conventional systematic review terms. | |
Meta-ethnography | An interpretive method for synthesising qualitative research of particular value in developing models that interpret findings across multiple studies. | Theoretical sampling [34] | Interpretive focus places premium on identifying studies to contribute added value over and above current version of synthesis and thus requires sampling on a theoretical basis. |
Meta-interpretation | A meta-synthetic approach used specifically in interpretative synthesis. | Maximal divergent sampling/maximum variation sampling [70, 72]; Theoretical sampling [70] | Focus on interpretation requires that insights are maximised by exploring papers that are not characteristic of the “average sample.” |
Meta-narrative synthesis | Takes paradigmatic approach to map literatures from different research traditions. | Seeks an illuminative sample of papers from within different research traditions. | |
Qualitative meta-synthesis | Attempts to integrate results from multiple different but inter-related qualitative studies with interpretive, rather than aggregating, intent, in contrast to meta-analysis of quantitative studies. | Comprehensive (representative) sampling [55] | Patterned on conventional systematic review methods therefore seeks all relevant studies to represent entire phenomenon of interest. |
Realist synthesis | Approach to complex social interventions or programmes which provides explanatory analysis aimed at discerning what works for whom, in what circumstances, in what respects and how. | At different points uses variously: (a) Comprehensive sampling [74]; (b) Purposive sampling [66]; (c) Theoretical sampling [34]; (d) Snowball sampling [61] | Comprehensive sampling (a) used to explore key focus of review. Becomes starting point for more explanatory exploration (b–d) of associated literature and mechanisms. |
Scoping review | Rapid review that aims to map existing literature in a field of interest in terms of volume, nature, and characteristics of primary research. | Random sampling [74] | Aims to characterise literature, not to document studies in minute detail, sampling representative body of literature may suffice for planning purposes. |