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Systematic Reviews

Data Extraction

Data Extraction

Your next step is extracting the necessary data from your included studies as this will assist in assessing the validity of the studies you're including in your review. The Cochrane Handbook provides a detailed table on data extraction, however, you may decide to select only some of these elements. There is also the Cochrane data collection form that can be used to extract data from randomised controlled trials.

Collection of Data & Templates

The term data refers to any information within the included studies, including information relating to the characteristics of the study as well as to quantitative and/or qualitative results.

How to know what data to collect?

The protocol defines the data that is to be extracted from each study, who will do the extracting and in what format it will be collected.

Data should also be systematically collected relating to the design and the methods of the research study, such as the use of randomisation and allocation concealment in RCTs. The protocol defines which specific statistical variables will be extracted such as the mean, confidence intervals or standard deviation.

How to avoid errors in data collected?

Methods to avoid the introduction of errors such as incorrectly entering numbers in a spreadsheet, failing to identify study characteristics that need to be recorded or bias that can be present in studies, should be considered. This may involve the use of two independent reviewers.

Tools for Data Extraction

Covidence logo

Covidence

Covidence is an online systematic review program developed by, and for, systematic reviewers. It can import citations from reference managers like EndNote, facilitate the screening of abstracts and full-text, populate risk of bias tables, assist with data extraction, and export to all common formats.

Covidence is a core component of Cochrane's review production toolkit and has recently also been endorsed by JBI.

Which version of Covidence is best for you?

  • Free trial version: for anyone wanting to try Covidence and find out whether it is suitable for their project. Gives you 1 free review for 2 reviewers

SR Tool Box logo

Systematic Review Tool Box

The Systematic Review Toolbox is a community-driven, searchable, web-based catalogue of tools that support various tasks within the systematic review and wider evidence synthesis process.

The toolbox aims to help researchers and reviewers find the following:

  • Software tools
  • Quality assessment / critical appraisal checklists
  • Reporting standards
  • Guidelines

Users can perform a simple keyword (i.e. Quick) search to locate tools, or a more detailed (i.e. Advanced) search allowing users to select various criteria to find specific types of tools.