A literature review is both a product and a process.
As a product, it is a thoughtfully crafted analysis, interpretation, evaluation, and synthesis of existing published work on a given topic. It highlights what is already known and explores the methods, models, theories, and concepts others have used in relation to the topic.
As a process, it involves several ongoing and repetitive steps:
Scoping reviews provide a preliminary assessment of the size and scope of existing research literature, aiming to identify the nature and extent of available evidence, often including ongoing studies.
Unlike mapping reviews which are more focused on specific questions, scoping reviews are broader and topic-based. Scoping reviews:
Adapted from Reviewing Research Guide, https://research.lib.buffalo.edu/literature-scoping-systematicreviews/introduction
Systematic reviews, widely used across evidence-based fields, follow a specific methodology designed to thoroughly identify all relevant studies on a particular topic and select studies based on clear, predefined criteria.
Key features include:
Adapted from Reviewing Research Guide, https://research.lib.buffalo.edu/literature-scoping-systematicreviews/introduction
Meta-analysis is a set of statistical techniques used to combine and synthesize quantitative data across multiple studies. It systematically evaluates, summarizes, and integrates findings to draw more robust conclusions. While it can be conducted independently, it is most often performed as part of a systematic review.
Systematic reviews aim to gather and assess empirical evidence that meets pre-established eligibility criteria to answer a specific research question. Meta-analysis, as a quantitative and formal epidemiological approach, enhances this process by providing more precise estimates of effects, such as treatment outcomes or risk factors.
Importantly, while meta-analyses are nested within systematic reviews, not every systematic review includes a meta-analysis.
A meta-analysis is suitable when studies report quantitative results, examine similar constructs or relationships, use comparable research designs, and focus on basic relationships between two variables, rather than results adjusted for additional factors.