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Covidence

Data Extraction

Extraction progress pageThe data extraction process can be complicated.  Covidence has developed several videos and instructional guides to assist you in the process.  Links to these resources appear throughout this guide.  It's important to consider the options available BEFORE starting the extraction process.

Projects created in Covidence, by default, use a format called "Extraction 2.0".  This newer format has been recently designed and built to be more flexible and intuitive than the older "Extraction 1.0" format.  You can, however, change your project to use the 1.0 format in the Settings menu.  

You can switch between extraction formats even after you start extracting but note that work started in one format will not transfer to the other.  You might consider testing in both formats before making a decision.

You can change between the two extraction formats by selecting, Settings -> Review Settings.

IMPORTANT: If you plan to do a Cochrane Review, or are doing any review that involves gathering outcome data or intervention data or if you'll want to export to Review Manager (RevMan), Covidence suggests you continue to use the 1.0 format. 

Extraction format flow chart

Extraction 2.0

The 2.0 format allows you to start with basic templates (Data Extraction & Quality Assessment) that are built into the system.  You can edit the existing options or you can select "I want to start from scratch" and build from the ground up!

You can access the Data Extraction and Quality Assessment Templates on the Extraction Screen. As you work on your template, you can save changes and come back later to finalize the template. When it's ready, you can "Publish" it. You can make changes to a template later but will need to review any studies that you've already 'extracted' to update the new data.  Covidence will give you a heads-up that a reference needs to be reviewed again if you do decide to change a template that you've published.

The default Quality Assessment template is Cochrane’s Risk of Bias. If you want to use a different tool, select I want to start from scratch in the Editor to delete the RoB domains and start with an empty template.

Once you've set up your templates you can click "Begin Extraction" in any study and begin filling in the content you wish to extract.  You can save work in progress and return to a specific study later. Once extraction has been completed for a study, click the "Send for Consensus" button. It is possible to revisit a form and edit even after it's been sent for consensus!

After extraction is completed, a project member will need to "Begin Consensus". The Consensus Screen will display a running total of conflicts to be resolved.

More Help Available

Extraction 1.0

The Extraction 1.0 format is an earlier template that will eventually be retired.  It still exists because there are features not yet added to the more recently developed 2.0 format.

  • If your review involves gathering outcome data or intervention data or if you'll want to export your data to Review Manager (RevMan), Covidence suggests you  use the 1.0 format
  • You must select 1.0 in the Covidence Settings are.  Go to, Settings -> Review settings -> "Select your preferred data extraction template" [bottom of screen].

When you open the 1.0 Data Extraction form, you will notice that it's approximately structured in the PICO format. With identification, methods, population, interventions, and outcomes sections available to for input.

The tables you set up for your first study will become the "Review Template". The additions/changes you make will be carried over to the next study you begin extracting.  Only the first reviewer can edit the template. The first reviewer can be changed at any time by clicking "Manage reviewers" on the study's pane Extraction page.

If you make a change to your tables in a later study, that becomes the new "Review Template and any new studies will use this new template.  Older studies that you have extracted will not include the revised information.  This may cause you to have multiple extraction templates for your studies.  That's why it's important to have a well-thought-out plan before initiating the Extraction process.

Please review the help below to learn how to create your data extraction forms.