In the data synthesis section, you need to present the main findings of your evidence synthesis. As an evidence synthesis summarizes existing research, there are a number of ways in which you can synthesize results from your included studies.
If the studies you have included in your evidence synthesis are sufficiently similar, or in other words homogenous, you can synthesize the data from these studies using a process called “meta-analysis”. As the name suggests, a meta-analysis uses a statistical approach to bring together results from multiple studies. There are many advantages to undertaking a meta-analysis.
If the studies you have included in your evidence synthesis are not similar (e.g. you have included different research designs due to diversity in the evidence base), then a meta-analysis is not possible. In this instance, you can synthesize the data from these studies using a process called “narrative or descriptive synthesis”.
A word of caution here – while the process underpinning meta-analysis is well established and standardized, the process underpinning narrative or descriptive synthesis is subjective and there is no one standard process for undertaking this.
In recent times, evidence syntheses of qualitative research is gaining popularity. Data synthesis in these studies may be termed as “meta-synthesis”. As with narrative or descriptive synthesis, there are a myriad of approaches to meta-synthesis.
(this content courtesy of University of South Australia Library)
Librarians can help write the methods section of your review for publication, to ensure clarity and transparency of the search process. However, we encourage evidence synthesis teams to engage statisticians to carry out their data syntheses.