Covidence

The purpose of the data extraction process is to provide evidence which answers your PICO question. 

Data Extraction Guidelines

• Create a standardized data extraction form
• Document guidance for the form will be used and applied and ensure all team members understand
• Describe the planned data extraction and develop a draft extraction form for your protocol
• Test your draft data extraction form on each type of study included in the review
• Have at least 2 researchers independently extract the data from each included study
• Develop a plan for resolving disagreements in data extraction

Examples of data extracted for an intervention question: 

• Author(s), year of publication, title, DOI
• Study type, participant recruitment/selection/allocation, level of evidence, study quality
  • sample sizes, effect size, dependent variables, reliability measures, pre and post-test data and statistical tests applied
• Participant demographics
• Intervention
• Outcomes

For additional data extraction criteria refer to: 

and remember to review similar systematic reviews for examples of data extraction

For a smooth data extraction process with less risk of bias: 

• Use existing systematic reviews on your topic to identify what information to collect if you are not sure what to do.
• Train the review team on the extraction categories and what type of data would be expected.  A manual or guide may help your team establish standards.
• Pilot the extraction / coding form to ensure data extractors are recording similar data. Revise the extraction form if needed.
• Discuss any discrepancies in coding throughout the process.
• Document any changes to the process or the form.  Keep track of the decisions the team makes and the reasoning behind them.

*Tips provided by UNC Systematic Review service