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Systematic Reviews: Collecting/Combining

PIECES: Systematic Review Process


Collecting/Combining the Studies

  • Collate and combine multiple reports of the same study.
  • Perform data extraction. To reduce bias and potential for errors, at least two reviewers should separately independently code each study with a preset form or data extraction too, collecting study details such as methods and design, participants, setting, interventions, results, etc. One reviewer may extract data as long as a second reviewers checks for accuracy. A third reviewer should resolve conflicts. It is recommended to pilot data extraction for a few studies before data extraction to determine important information to collect.
  • Either qualitatively or quantitatively synthesize extracted data. If data are homogenous, perform a meta-analysis.


University of York. Centre for Reviews and Dissemination, & Akers, J. (2009). Systematic reviews: CRD's guidance for undertaking reviews in health care. Centre for Reviews and Dissemination.

Systematic Review Management Tools

  • DistillerSR - This fee-based online application is designed to assist with abstract and full-text screening, as well as data extraction and data output.
  • Rayyan QCRI - Rayyan is a free systematic review management tool designed to help researchers working on systematic reviews and other knowledge synthesis projects. Rayyan's platform allows research teams to collaborate, screen, and select studies.
  • Systematic Review Data Repository (SRDR) - From the Agency for Health Research and Quality, SRDR is a free and easy-to-use tool for data extraction and management designed specifically for systematic reviews. In addition to providing data management and storage, SRDR also contains a repository of data from other systematic reviews, with the option to publish your data when your review is complete.
  • Systematic Review Toolbox - More free systematic review tools are available online. You can search these tools and find associated articles through the Systematic Review Toolbox.

Citation Management

Citation Management Tools

Citation management tools allow you to store and organize citations and files, as well as to create bibliographies formatted in major citation styles (MLA, APA, Chicago, etc.).

Mendeley is a reference manager that allows you to create a personal database of references related to your research, access or upload data, and insert citations into Word using any one of thousands of citation styles. If you are collaborating with other researchers, Mendeley allows you to share references. We have a LibGuide to using Mendeley.

Mendeley LibGuide
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Zotero is a free, open source citation manager that works as a browser plugin and also as a stand alone application on your computer. Zotero's browser plugins can automatically extract citation information from websites, library catalogues, databases and more. It also allows you to save PDFs, images, screenshots and notes along with the citation records you create. Zotero automatically indexes the full-text content of your library, enabling you to find exactly what you're looking for with just a few keystrokes. Zotero keeps your library synced in the cloud, so you can access it from any computer, or mobile device.

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EndNote is bibliographic software that is available for purchase and installation on your computer. It will allow you to save and organize references, images, and other files and to create formatted bibliographies. EndNote Web is a component of EndNote that is available through the FSU Libraries. With EndNote Web, you can collect and organize references, format a bibliography, collaborate with others, and export references to an EndNote account.

Log into EndNote Web, find out more, or register for an account

Data Extraction Process

Data Extraction Overview

Whether you plan to perform a meta-analysis or not, you will need to establish a regimented approach to extracting data. Researchers often use a form or table to capture the data they will then summarize or analyze. The amount and types of data you collect, as well as the number of collaborators who will be extracting it, will dictate which extraction tools are best for your project. Programs like Excel or Google Spreadsheets may be the best option for smaller or more straightforward projects, while systematic review software platforms can provide more robust support for larger or more complicated data.

It is recommended that you pilot your data extraction tool, especially if you will code your data, to determine if fields should be added or clarified, or if the review team needs guidance in collecting and coding data.

Data Extraction Tools


Excel is the most basic tool for the management of the screening and data extraction stages of the systematic review process. Customized workbooks and spreadsheets can be designed for the review process. A more advanced approach to using Excel for this purpose is the PIECES approach, designed by a librarian at Texas A&M. The PIECES workbook is downloadable at this guide.


Covidence is a software platform built specifically for managing each step of a systematic review project, including data extraction. Read more about how Covidence can help you customize extraction tables and export your extracted data.  


RevMan is free software used to manage Cochrane reviews. For more information on RevMan, including an explanation of how it may be used to extract and analyze data, watch Introduction to RevMan - a guided tour.


SRDR (Systematic Review Data Repository) is a Web-based tool for the extraction and management of data for systematic review or meta-analysis. It is also an open and searchable archive of systematic reviews and their data. Access the "Create an Extraction Form" section for more information.


DistillerSR is a systematic review management software program, similar to Covidence. It guides reviewers in creating project-specific forms, extracting, and analyzing data. 


JBI Sumari (the Joanna Briggs Institute System for the United Management, Assessment and Review of Information) is a systematic review software platform geared toward fields such as health, social sciences, and humanities. Among the other steps of a review project, it facilitates data extraction and data synthesis. View their short introductions to data extraction and analysis for more information.

The Systematic Review Toolbox

The SR Toolbox is a community-driven, searchable, web-based catalogue of tools that support the systematic review process across multiple domains. Use the advanced search option to restrict to tools specific to data extraction. 

Data Extraction Forms

These resources offer additional information and examples of data extraction forms:​

Brown, S. A., Upchurch, S. L., & Acton, G. J. (2003). A framework for developing a coding scheme for meta-analysis. Western Journal of Nursing Research25(2), 205–222.

Elamin, M. B., Flynn, D. N., Bassler, D., Briel, M., Alonso-Coello, P., Karanicolas, P. J., … Montori, V. M. (2009). Choice of data extraction tools for systematic reviews depends on resources and review complexity. Journal of Clinical Epidemiology62(5), 506–510.

Higgins, J.P.T., & Deeks, J.J. (Eds.) (2011). Chapter 7: Selecting studies and collecting data. In J.P.T.Higgins, & S. Green (Eds.), Cochrane handbook for systematic reviews of interventions Version 5.1.0 (updated March 2011). The Cochrane Collaboration. Available from

Research guide from the George Washington University Himmelfarb Health Sciences Library:

Data Extraction & Exportation in Covidence

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