Being aware of the type of methodology used in a study is an important part of the research process. Many indexes -- such as PsycINFO -- provide limits to restrict your search results by methodology type.
A meta-analysis is a statistical analysis that combines the results of multiple scientific studies. Further further reading on the differences between systematic reviews and meta-analyses, see Garg et al.'s "Systematic Review and Meta-analysis: When One Study Is Just not Enough" CJASN January 2008, vol. 3 no. 1, 253-260. Another 'must read' article on the benefits of systematic reviews and meta-analyses as they pertain to organizational behavior is Kevin Daniels' "Guidance on conducting and reviewing systematic review (and meta-analyses) in work and organizational psychology" EJWOP November 2018.
For definitions of each methodology, visit the following APA Databases Methodology Field Values webpage.
For the purposes of MIR-850, Dr. Lilius has provided a list of research methodology types, arranged in descending order of strength. To summarize, the more meta-analyses and systematic reviews you identify to support your case, the better. Bear in mind that the number of systematic reviews (or meta-analyses) available on a specific topic may be scant so you may need to broaden your search.
To demonstrate the levels of evidence graphically, a pyramid has been used. It demonstrates the progression from 'less evidence-based' at the bottom of the pyramid, where the greatest bulk of literature is found, to more 'evidence-based' at the top where there is much less available literature due to the increased complexity of the scientific process. One such pyramid is as follows:
(Image attributed to https://libguides.cmich.edu/cmed/ebm/pyramid)
In the library session you will be shown how to limit your searches to include only results that adopted a particular methodology.