Combining findings from different research

1. Combining findings from different research Qualitative versus quantitative approach The EBM workshop A.A.Haghdoost, MD; PhD of Epidemiology Ahaghdoost@kmu.ac.ir

2. Rational Researchers used to think the aim of a single study was to decide if a given effect was "real" (statistically significant). But they put little faith in a single study of an effect, no matter how good the study and how statistically significant. Combining evidences

3. Rational Each study produces a different estimate of the magnitude. When many studies were done, someone would write a narrative (= qualitative) review trying to explain why the effect was/wasn't real in the studies. Or would carry out a study to estimate the magnitude of an effect with adequate precision using others’ findings. Combining evidences

4. Quantitative approach Meta-analysis combines the effects from all studies to give an overall mean effect and other important statistics. The measured effects should be comparable and estimate a common quantity Combining evidences

5. Qualitative approach If studies measured different parameters, such as measurement of depression using different questioners If someone would like to combine the findings of qualitative studies Combining evidences

6. Meta analysis Meta synthesis Pure Replications Conceptual Replications Combining evidences

7. Guideline Clinical practice guidelines are recommendations for clinicians and consumers about optimal and appropriate care for specific clinical situations Nowadays, formal guideline are generated by using both qualitative and quantitative methods Combining evidences

8. Meta synthesis • “Putting together” findings from qualitative studies • A relatively vague and little known comparative method of synthesizing qualitative studies – for the “accumulation of knowledge” Combining evidences

9. Methodology of meta-synthesis (1) Systematic review?! Focus on search strategies, quality and aggregation “A critical assessment and evaluation of research (not simply a summary) that attempts to address a focused clinical question using methods designed to reduce the likelihood of bias.” Guyatt and Rennie 2002 Combining evidences

10. Methodology of meta-synthesis (2) Since the papers are usually extremely heterogeneous, you can group the articles into categories of similar domains. For each article, central themes should be extracted and common metaphors identified for the whole category. Content analysis and compare the similarity and differences between study findings Combining evidences

11. Arguments in Favor of Meta-Synthesis • Qualitative research may be endangered and marginalized by its failure to sum up or put together – and not be “little islands of knowledge” • Need to compare findings and data – in the same topical area • Need to extend beyond modernism to post modernism Combining evidences

12. Arguments Against Qualitative Meta-synthesis • You can’t sum up poems or songs! • Variations of method and underlying theoretical assumptions • Diversity of practices • Destroys the integrity of individual studies • Thins our deep descriptions • De-contextualizes material Combining evidences