Systematic Review: 2. Apply criteria

As each reviewer assesses the articles returned by the searches, they must adhere to the inclusion and exclusion criteria that were defined in the protocol.  A checklist or table will assist with this.  See example table below:

You can create your own table, or use a template or screening tool:

Screening workbook

Covidence

Your table also serves as a documentation of each reviewer's rationale in selecting or rejecting articles.  A "cross check" is performed to make sure that all reviewers have agreed on the included articles (based on their abstracts).  The full texts of the included articles are retrieved at this point.

There are a number of ways to do this:

The screening process is then repeated for remaining articles, this time based on the full-text of each source.  Again, this step is usually performed independently by multiple reviewers to reduce bias.  Reviewers then compare their results until agreement is reached.  Sometimes an additional reviewer is needed at this stage if inclusion of any articles is particularly contentious.  The articles remaining are the ones which will be evaluated and analysed.