8. Synthesise studies

How systematic should you be?

The stages of a systematic review

1. Produce a review protocol / plan

2. Assemble a review group / advisory group

3. Formulate review question(s)

4. Conduct a thorough search

5. Select relevant studies

6. Appraise the quality of studies

7. Extract information from individual studies

8. Synthesise studies

9. Report what is known and not known

10. Inform research, policy and practice

8. Synthesise studies

Systematic reviews have processes for synthesizing multiple studies in order to provide results that are more than the sum of the parts. As with any method, the approaches chosen should be appropriate to the purpose of the study and the nature of the available data.

As noted by Hart (1998, p. 110) this usually involves a two-step process:

Analysis,

•"…is the job of systematically breaking down something into its constituent parts and describing how they relate to each other – it is not random dissection but a methodological examination."

•

Synthesis,

•"…is the act of making connections between the parts identified in analysis. It is about recasting the information into a new or different arrangement. That arrangement should show connections and patterns that have not been produced previously."

The purpose of the synthesis can be to:

develop a narrative - description, explanation, argument, interpretation or a combination of these

qlink two areas of literature

qcreate a model or framework

qexamine propositions / questions

qdevelop theory

measure the effect of an intervention (e.g. meta-analysis)

The process of synthesis is a key challenge for inexperienced researchers and is a skill that is developed through experience. As noted by Ray Pawson,

“Evidence, new or old, numerical or narrative, diffuse or condensed, never speaks for itself. The analysis and usage of data is a sense-making exercise” (Pawson, 2001: 17)

There are multiple approaches to synthesis. Please refer to Rousseau, Manning and Denyer (2008) who differentiate between aggregative, interpretative, integrative and explanatory forms of synthesis. Also see Denyer and Tranfield (2006) for a discussion of qualitative approaches to synthesis and Denyer, Tranfield and Van Aken (2008) for a discussion of explanatory synthesis.

Please remember that the method of synthesis must:

•be appropriate to the research being synthesised

•cope with diffuse and heterogeneous data

•go beyond a description

•provide enough detail from the original studies to allow the reader to interpret the results

•give an audit trail linking the key findings of the studies to the conclusions

References

Denyer, D. & Tranfield, D. (2006). Using qualitative research synthesis to build an actionable knowledge base, Management Decision, Vol. 44, 213 - 227.

Denyer, D., Tranfield, D. & van Aken, J.E. (2008). Developing design propositions through research synthesis, Organization Studies, Vol. 29, 393-413.

Hart, C. (1998) 'Doing a literature review: releasing the social science research imagination', London: SAGE Publications

Pawson, R. (2001) 'Evidence Based Policy: I. In search of a method'. Working Paper 3. ESRC Centre for Evidence Based Policy and Practice, Queen Mary, University of London. (Pre-publication version: submitted to Evaluation).

Rousseau, D.M., Manning, J. & Denyer, D. (2008). Evidence in Management and Organizational Science: Assembling the field’s full weight of scientific knowledge through syntheses. In A. Brief & J. Walsh (Eds.), Annals of the Academy of Management, Vol. 2., No. 1, 475-515

The text on this page was created by Professor David Denyer, Professor of Organizational Change, Cranfield School of Management.