Evidence Synthesis, Systematic Review Services : Extract Data

Once your research team has determined the studies that satisfy their criteria for review, the team will then extract data from these studies to analyze and summarize. This process of data extraction is generally achieved by creating, pilot-testing (using a few selected articles), and populating a data extraction form or evidence table to which the team agrees. As with the article/paper screening process, two or more team members will extract the data independently then compare to reach consensus. Your protocol will indicate and describe the data to be extracted and coded, whether you apply any standardized instrument or software tool to the process, and how the team will manage ambiguous information or obtain any missing data for the studies they intend to review.

The data you extract will be that data which is necessary and relevant to answering your research question and may include the following: 

• bibliographic/citation information (title, authors, year of publication)
• study site (field or lab) and geographic location
• population or demographic characteristics
• methodology and experimental conditions
• interventions (dosing, time-frame, quantity)
• comparators (description of the control)
• outcomes (quantitative and/or qualitative)

Helpful toward this process will be to review the framing of your research question (PICO, among others) and your eligibility criteria for including and excluding studies. Do also examine your benchmark articles, noting the data elements you would want to capture. Your team may also want to consider using an existing template or tool for guidance (see links to selected tools, below) or examples from the published evidence synthesis/systematic reviews literature.