A meta-analysis is a specific kind of review that goes beyond collecting and appraising studies to answer a particular question. It involves doing a well executed systematic review to include studies similar in design so that their data can be combined to establish "a more precise effect of the results." The benefits of this approach is that smaller studies that do not show statistically significant results can be combined with other studies to strengthen the overall effect size of an intervention. The down side of this approach is that investigators need to be sure they are not including studies that are dissimilar to one another.
Source:
Grant, M.J. and Booth, A. (2009), A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26: 91-108. https://doi.org/10.1111/j.1471-1842.2009.00848.x
A rapid review is defined by Hamel et. al (2021) as ‘‘a form of knowledge synthesis that accelerates the process of conducting a traditional systematic review through streamlining or omitting a variety of methods to produce evidence in a resource-efficient manner.’’ According to Grant & Booth (2009) this approach offers researchers the opportunity to employ methods that will speed up the process of the review and documenting the effect these changes would have. This includes the use of broader search strategies, reviewing reviews, limiting the amount of grey literature, and simplifying the appraisal process. The risk of this approach, they state, is the introduction of bias.
Sources:
Grant, M.J. and Booth, A. (2009), A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26: 91-108. https://doi.org/10.1111/j.1471-1842.2009.00848.x
Hamel C, Michaud A, Thuku M, Skidmore B, Stevens A, Nussbaumer-Streit B, Garritty C. Defining Rapid Reviews: a systematic scoping review and thematic analysis of definitions and defining characteristics of rapid reviews. J Clin Epidemiol. 2021 Jan;129:74-85. doi: 10.1016/j.jclinepi.2020.09.041. Epub 2020 Oct 8. PMID: 33038541.
A mapping review is an approach that seeks out literature on a topic and then categorizes the results. This is an effective means to identifying gaps in the literature and to justify the need for a more comprehensive review or even more original research on the subject. This is why they are different from scoping reviews.
Source:
Grant, M.J. and Booth, A. (2009), A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26: 91-108. https://doi.org/10.1111/j.1471-1842.2009.00848.x