Systematic reviews (SRs) and meta-analyses (MAs) sit on top of the evidence hierarchy:
What Are They Again? How Are They Different?
SRs and MAs both provide robust evidence for a research question because they synthesize information from multiple studies. However, they are not the same thing.
A SR uses a detailed and transparent method to identify, appraise and synthesise all of the relevant research on a well-defined question.
In contrast, a MA uses statistical techniques to combine the results from multiple studies into a single quantitative estimate or summary effect size.
Therefore, a SR refers to the entire process of selecting, evaluating, and synthesizing all available evidence, while a MA refers to the statistical approach to combining the data derived from a SR.
SRs will often, but not always, contain a MA.
How To Find Systematic Reviews and Meta-analyses
TIP: Check your introduction for anywhere you have made statements such as this: “there is substantial evidence that [X] is related to [Y] (reference, reference, reference, reference)". If you have found numerous studies in relation to a specific research question, then I would check if a SR or MA exists.
When you use the Advanced Search feature of databases such as APA PsychInfo, you often have the option to select MA or SA under "Methodology".
Alternatively, if you can't find this search option, you can just include "systematic review" and "meta-analysis" as additional search terms.
If you are researching a health-related topic, I recommend checking out the Cochrane Library. The Cochrane Library is home to the Cochrane Database of Systematic Reviews, which is the leading database for SRs in health-care treatments and interventions.
How to Report the Results of a Meta-Analysis
When you report the results of a MA, I recommend including the:
Number of studies
Number of participants
Effect sizes
For example,
“Recent meta-analytic evidence suggests mindfulness-based cognitive therapy (MBCT) is also effective for treating acute depression. Thimm and Johnson’s (2020) meta-analysis of 20 studies (N = 824) found MBCT was effective in reducing self-reported depressive symptoms, with the average effect sizes being large for both between-groups studies comparing MBCT to no-treatment control groups, and pre-post studies.”
TIP: Keep in mind you only need to report details of key studies. If one of your references is a SR/MA, but it is not a key study, you can just let the reader know this high quality evidence exists. For example: "There is extensive evidence that [X] is related to [Y] (for a systematic review and meta-analysis, see reference [year])."
Happy Researching!
***If you want more strategies and tips for how to effectively conduct a literature review, enrol in my on-demand workshop, Learn How to Write a Kick Ass Thesis: Part 1 - Setting Yourself up For Success***
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