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Systematic Reviews

This guide is intended for students, research assistants and faculty who are planning to undertake a systematic review, or who are interested in applying systematic research methods to a current project.

Step 4: Selecting Studies For Inclusion

Once you have executed your search, you will need to select which studies meet your inclusion criteria, and which will be excluded from your review - also known as screening. Note that for systematic reviews, it is recommended that at least two reviewers screen the results independently. This is to help resolve disagreement by encouraging consensus and reduce the risk of biased decisions. 

The following steps will be useful to consider at the screening stage:

  • De-duplicate references - when searching more than one resource, it is inevitable that you will have duplicate results. You will want to document the number of duplicates you have prior to any deletion. The use of citation management tools can be helpful when storing and organizing large numbers of citations. 
  • Initial screening of titles and abstracts for relevance - this is where you will apply your inclusion criteria, identify which studies meet those criteria, and which ones will be excluded. Paper or electronic screening forms can be useful for this process.  At this point, you are simply screening the title and abstract to see if it meets your criteria - a more deeper assessment of the full-text will take place later on. In order to minimize bias, at least two reviewers will be screening titles and abstracts independently of each other. Once both reviewers have completed this task, they should meet up to discuss their results and resolve any discrepancies. Pilot your screening with about 50 records to start, to ensure accuracy and relevancy.
  • Read full-text of potential studies - retrieve and read the full-text of studies. If you need access to studies not available at the TMU Library, make use of our InterLibrary Loan to access collections at other Ontario university libraries. 
  • Secondary screening of full-text paper for inclusion in review - at this stage, you must determine if the studies you included at the initial screening phase actually meet your inclusion criteria by screening the full text. Again, pilot your screening with a few articles. Keeping track of why studies are being excluded is encouraged and can be easily done if you are using citation management tools or electronic forms. 
  • Track and document your results - keeping precise documentation of your process is a key component of any systematic review, and will help when writing up the methods and results section.  It will also help anyone who wants to executive a similar review in the future, or update your review in the future. 
  • Research data management - reviews create a lot of data, and planning a process for managing the data will help with transparency, replicability and reproducibility. The University of Calgary has a guide which provides additional guidance and examples for creating a data management plan for your systematic review (or other knowledge synthesis) project using Canada's DMP Assistant template for Systematic Reviews