Introduction to Systematic Reviews

Before You Start Checklist

Are you ready to carry out a knowledge synthesis project such as a systematic review, meta-analysis, or scoping review? Remember that systematic reviews require:

  • a team to carry out screening, extraction, and critical appraisal methods
  • a significant amount of time to complete
  • enough high quality studies to make a systematic review feasible
  • a rigorous protocol (that should be registered)
  • adherence to transparent and rigorous methods
  • a strong project management component with defined goals, responsibilities, deliverables, and timelines 
  • financial resources to complete the project 

What Review Is Right For You?

If you're unsure what type of knowledge synthesis best suits your research purposes, follow along this flowchart or complete this short quiz to find your personalized review methodologies:

Reproduced from "What type of review could you write?" Yale Medical Library. 

Types of Knowledge Syntheses

Conducting effective reviews is essential to advance the knowledge and understand the breadth of research on a topic; synthesize existing evidence; develop theories or provide a conceptual background for subsequent research; and identify research gaps. However, there are over 100 different kinds of reviews to choose from. The following provides a comparison of common review types.

Review Type






Literature review

Generic term: published materials that provide an examination of recent or current literature. Can cover a wide range of subjects at various levels of completeness and comprehensiveness. May include research findings

May or may not include comprehensive


May or may not include quality


Typically narrative

Analysis may be chronological, conceptual, thematic, etc.

Systematic review

Seeks to systematically search for, appraise and synthesize research evidence, often adhering to guidelines on the conduct of a review

Aims for exhaustive,

Comprehensive searching

Quality assessment

may determine


Typically narrative

with tabular


What is known; recommendations

for practice. What remains unknown; uncertainty around findings, recommendations for

future research


Technique that statistically combines the results of quantitative studies to provide a more precise effect of the results

Aims for exhaustive searching. May use funnel plot to assess completeness

Quality assessment may determine inclusion/exclusion and/or sensitivity analyses

Graphical and tabular with narrative commentary

Numerical analysis of measures of effect assuming absence of heterogeneity

Scoping review

Preliminary assessment of potential size and scope of available research literature. Aims to identify the nature and extent of research evidence (usually including ongoing research)

Completeness of searching determined by time/scope constraints. May include research in progress

No formal quality assessment

Typically tabular with some narrative commentary

Characterizes quantity and quality of literature, perhaps by study design and other key features. Attempts to specify a viable review

Mixed studies review/mixed methods review

Refers to any combination of methods where one significant component is a literature review (usually systematic). Within a review context, it refers to a combination of review approaches for example combining quantitative with qualitative research or outcome with process studies

Requires either very sensitive search to retrieve all studies or separately conceived quantitative and qualitative strategies

Requires either a generic appraisal instrument or separate appraisal processes with corresponding checklists

Typically both components will be presented as narrative and in tables. May also employ graphical means of integrating quantitative and qualitative studies

Analysis may characterize both works of literature and look for correlations between characteristics or use gap analysis to identify aspects absent in one literature but missing in the other

Umbrella review

Specifically refers to review compiling evidence from multiple reviews into one accessible and usable document. Focuses on a broad condition or problem for which there are competing interventions and highlights reviews that address these interventions and their results

Identification of component reviews, but no search for primary studies

Quality assessment of studies within component reviews and/or of reviews themselves

Graphical and tabular with narrative commentary

What is known; recommendations for practice. What remains unknown; recommendations for future research


Reproduced from Grant, M. J., & Booth, A. (2009). A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26(2), 91-108. DOI: 10.1111/J.1471-1842.2009.00848.X