Module 1: Types of Reviews
Systematic Reviews
What Are Systematic Reviews?
A systematic review is also known as evidence synthesis because it brings together information from a range of sources to answer a specific research question. It differs from a traditional literature review, in that it aims to and the research in an unbiased, rigorous and way so that it can be used to support evidence-based practice.
Characteristics
- The scope of the review is established in advance (including the research question and pre-defined eligibility criteria).
- A systematic search is conducted in order to identify all studies/resources that would meet the eligibility criteria.
- The methodology used to search, assess, analyze and synthesize studies/resources is explicit and reproducible.
- The review assesses the validity of the studies/resources for a risk of .
- The review uses explicit methods for extracting and synthesizing study findings ( or ).
Types of Systematic Reviews
There are different types of reviews that involve evidence synthesis and a systematic review is the most well known version. Other examples include a rapid review or a scoping review. We define the different types in more detail below.
Example
Learning Activity
Determine what type of review would be the best fit for each of the following research questions.
Teams and Time Considerations
A review like a systematic review or a meta-analysis can take at least a year to complete and is usually conducted by a team. If your review is for a class assignment, you can still conduct a systematic review without a team or a year to complete it. If your aim is to eventually publish your review, keep in mind that one of the main goals of a systematic review is to try and eliminate potential bias, and working independently can be viewed negatively. If you must work independently, you should identify this limitation when writing your review.
Systematic Reviews and Bias
Eliminating bias as much as possible is one of the key characteristics of systematic reviews. By bias, we mean that some type of systematic error has occurred during the review stage that leads to the acceptance of outcomes and conclusions of a study. This can result in the possibility of unfair or misleading information within the reviews. Bias is potentially introduced at any stage of the research process, from formulating your research question to choosing which sources to include.
In order to reduce bias in your review, you will need to undertake a quality assessment throughout the review process. Your protocol (see next section) and your process will help you reduce your bias. Another way to reduce bias is to work in a team setting, and this is why some reviews require more than one person. We will cover how to check for bias when screening sources in Module 3 Organizing, Managing and Screening Sources.
Why Are Systematic Reviews Important?
A systematic review can generally give us the most dependable answer to a specific research question, and it can identify gaps in our knowledge that require further research. It also communicates the strength of the available evidence and the quality of included studies. This indicates how much confidence practitioners, service users, managers, policy makers, and the popular media should have in the results (Gough & Richardson, 2018).
What Type of Systematic Review is Right for You?
Booth et. al (2016) suggest that your choice of review methods should be determined by five main considerations captured by the acronym, TREAD
These and other factors may determine what kind of review is most appropriate to answer your research question.
Learning Activity
Decision Tools
The following tools can help you pick the right systematic review:
- Knowledge Synthesis Decision Tool Unity Health Toronto Health Science Library, St. Michael’s Hospital
- Review Ready Reckoner – Assessment Tool (RRRsAT). Temple University Libraries
Key Takeaways
It is important to understand and meet the specific requirements of your chosen review, especially if you plan to publish your review.
Booth, A., Noye, J., Flemming, K., Gerhardus, A., Wahlster, P., Van Der Wilt, G.J., Mozygemba, K., Refolo, P., Sacchini, D., Tummers, M., Rehfuess, E. (2016). Guidance on choosing qualitative evidence synthesis methods for use in health technology assessments of complex interventions (PDF).
Gough, D., & Richardson, M. (2018). Systematic reviews. In Advanced research methods for applied psychology (pp. 63-75). Routledge.
The examining and combining of information with other information to produce a final interpretation, theory or conclusion.
To examine methodically and in detail the structure or elements of the information presented. Typically for purposes of explanation and interpretation.
Carried out using a planned, ordered procedure. Methodical.
Bias is a disproportionate weight in favor of or against an idea or thing. Example: when a systematic review does not identify all available data on a topic.
Qualitative research relies on data obtained by the researcher from first-hand observation, interviews, questionnaires (on which participants write descriptively), focus groups, participant-observation, recordings made in natural settings, documents, and artifacts. The data are generally nonnumerical.
Quantitative data can be counted, measured, and expressed using numbers.
The purpose of screening is to eliminate studies that do not meet your inclusion criteria. If you are a team, each team member should independently screen all studies, starting with a title and abstract, followed by a full-text screening.