Once you have selected the relevant studies to be included in your synthesis, a standardized data extraction form will help you obtain all relevant information from each paper so that you can examine and compare results.

As with both levels of the screening process, it is best practice to have two reviewers complete the data extraction form independently for each study, and to have a plan for resolving disagreement. 

In the data extraction phase your team should be using a standardized form tailored to your research question and review type. This step can be completed in any number of ways. 

What data do you need to collect?

The data that is relevant to the review will be different for every review. Some categories of data that might be included:

• Identification features (such as article title, author, citation, record number, type of publication, publication date, funding sources)
• Methods
• Participant characteristics
• Intervention and Setting
• Outcome/Results
• Study quality factors

How to collect the data?

Pre-specifying categories for form fields can help streamline the extraction process, and is especially useful when you plan on performing a quantitative analysis. When doing so, be sure to include, "other," "not reported," or "unclear" options. However, this is not appropriate for all review types and all data fields. 

For example, in the case of integrative, scoping, or qualitative systematic reviews, it may make more sense to have open data fields for outcomes. 

What to use to collect the data?

• Systematic review software (Distiller, Covidence, PICO Portal)
• Spreadsheet (Excel, Google Sheets)
• Survey Tool (Microsoft Forms, Survey Monkey)