Skip to Main Content

Treadwell's Service for Systematic, Scoping and Other Reviews

A guide to help with conducting comprehensive and non-comprehensive reviews

How Long Does a Comprehensive Review Take?

How Long Will the Entire Project Take?

Comprehensive projects like systematic and scoping reviews are work and time intensive! Estimates of the average time to conduct a comprehensive review range from six months to two years. Below is an example timeline for a systematic review from the Cochrane Collaboration:

cochrane timeline


How Long Will the Literature Search Take?

This varies by project as some research questions take more time than others. Timelines may be delayed if your project is waitlisted as well. Generally, once you've met with us, you can expect us to finish the search in about three weeks. This timeframe will also be extended if the group asks for a lot of revisions or if the team is slow to respond to our questions.


Isn’t There a Faster Way? I Don’t Have That Much Time!

Comprehensive reviews are rigorous methodologies and require a significant amount of time to conduct. If you need to conduct a review in less time, a different review methodology may be more appropriate, such as a:

  • Traditional narrative review
  • Rapid review

Rapid reviews typically take five weeks to complete. To learn more about the differences between these review types, read Evidence summaries: the evolution of a rapid review approach.

Steps to the Comprehensive Review Process

  1. Define your research question. Be as specific as possible, using operational definitions when appropriate.
  2. Based on your question, determine whether a systematic review is the best methodology for your review. See Grant's overview of 14 review types and methodologies. Also consider your available time and capacity. Will your team be able to systematically screen thousands of citations?
  3. Identify prior systematic reviews related to your topic. A librarian can help with this. Identifying prior systematic reviews can help you define the scope of your research question and determine how your review whether your review will add to the literature or merely replicate past work.
  4. Assemble your team. Generally, you will want at least two people to screen citations in order to reduce bias, someone with expertise in data synthesis (qualitative, quantitative, or mixed methods, depending on your plan), and an expert searcher (like a Treadwell librarian). 
  5. Determine study inclusion and exclusion criteria.
  6. Develop a plan of organization for your data. How will you keep track of the citations that you find? What is your plan for bias assessment/quality assesment, data extraction, and data synthesis?
  7. Formulate your research protocol. The PRISMA-P standards and checklist can be used to help you structure your protocol. It is recommended that you register your protocol in PROSPERO, an international systematic review protocol registry. The process of registration is straightforward and their guidance notes will tell you exactly what information to include.   
  8. Conduct a thorough literature search. A librarian can do this for you, or you can take our course to learn how to do it yourself. Bear in mind that this step takes a librarian several weeks to complete; it will take even longer if you plan to do it yourself.
  9. Select studies for inclusion.
    1. Use a random sample of your results to test interrater reliability & inclusion/exclusion criteria.
    2. Screen titles/abstracts.
    3. Resolve disagreements between screeners.
    4. Obtain full text and review full text, noting reasons for exclusion. 
    5. Resolve disagreements between screeners.
  10. Appraise the quality of the studies.
  11. Extract data using a standardized form. 
  12. Synthesize/analyze the data. 
  13. Interpret the results.
  14. Write up the report.