About systematic reviews

Decorative image
Photo by José Ignacio González Pansiera on Unsplash

A systematic review is a secondary research method that identifies and evaluates evidence from existing data in primary research studies.

Commonly, systematic reviews are used in healthcare research to assess the evidence on whether a medical intervention is effective in treating a certain condition.


As defined by the  Cochrane Collaboration a systematic review is:

“A review of a clearly formulated question that uses systematic and explicit methods to identify, select, and critically appraise relevant research, and to collect and analyse data from the studies that are included in the review. Statistical methods (meta-analysis) may or may not be used to analyse and summarise the results of the included studies.”

Features of a systematic review

A systematic review has these key features:

  1. It addresses a research question that is clearly defined and specific. 
  2. It follows a rigorous methodology by adopting a clearly pre-defined protocol. 
  3. It is an exhaustive search of the literature that is carried out in accordance with the protocol. 
  4. All evidence is considered and only excluded if it does not meet the eligibility criteria. 
  5. The included studies are critically analysed, especially for the risk of bias. 
  6. It ideally involves more than one person.

For HDR candidates

A PhD or a Masters by Research thesis will include a chapter devoted to a review of the literature. This type of review is known as a traditional or narrative review, or simply a literature review.

The following table outlines the different features of a systematic review and a traditional literature review.

Systematic review vs. Literature review

Features Systematic review Literature review
Aim Tightly specified objectives to answer a specific research question Gain a broad understanding and description of a field
Scope Narrow focus Big picture
Planning the review Transparent process with documented audit trail defined in a protocol Nothing defined, allows for creativity and exploration
Searches Rigorous and comprehensive search for ALL studies, explicit search strategy across numerous sources Searching is probing, moving from study to study, following-up leads
Study selection Predetermined criteria for including and excluding studies uniformly applied Selection is variable as determined by the reviewer
Appraisal Checklists to assess the quality of studies Based on the reviewer’s opinion
Synthesis Tabular format with short summary answers Discursive
Methodology Must be presented for transparency Not necessarily provided
Inferences Based on all available evidence Based on a sample of the evidence
Timeline Months to years (average 18 months) Weeks to months
Authors Three or more One or more
Value Connects practising clinicians to high-quality evidence; Informs evidence-based practice Provides a summary of literature on a topic

Watch the following short video to learn about the difference between a systematic review and a meta-analysis.

Systematic review vs Meta-analysis (5 mins)

Systematic review vs Meta-analysis (5 mins) by Research Masterminds (YouTube)

Some brief information about other types of reviews, such as scoping reviews, rapid reviews, and meta-analyses is available from the library guide: Systematic Reviews.

Benefits of a systematic review

EBM hierarchy
“File:Evidence-based Medicine (EBM).png” by Tingjoh is licensed under CC BY-SA 4.0

A systematic review has several advantages, including:

  • Being considered the highest level in the hierarchy of literature evidence.
  • Provides a definitive answer to a question, commonly about therapy, prevention, and causes of disease or harm.
  • The methods used to find and select studies reduce bias and are more likely to produce reliable and accurate conclusions. 
  • Summarises findings from multiple studies, reducing bias when drawing conclusions and making the findings more reliable.
  • Findings might be applied to everyday practice or to inform policy.
  • Identifies knowledge gaps that call for more research.


Benefits for HDR candidates

Conducting a systematic review provides several benefits: 

  • it fulfills the request made by your supervisor to conduct the systematic review
  • it contributes to your thesis
  • the paper can be published
  • it contributes to your research knowledge of the topic.


Test your knowledge



Icon for the Creative Commons Attribution-NonCommercial 4.0 International License

Research and Writing Skills for Academic and Graduate Researchers Copyright © 2022 by RMIT University is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

Share This Book