Systematic Reviews & Evidence Synthesis Guide

A protocol outlines your objectives, planned methodology, and eligibility criteria. Developing and publishing a prospective protocol is considered a best practice in conducting a systematic review. Publishing an a prior protocol (in advance of the work) is a requirement for many publishers and a recommendation of others. Additionally, publishing a complete protocol provides the authors with a set of guidelines to follow while working on the initial review and facilitates reliable reproducibility post-publication.

Elements of a Cochrane protocol

• Research Question (see next page for more on this)
• Background
• Objectives
• Methods
  • Criteria for selecting studies for this review (eligibility criteria):
    • Types of studies
    • Types of participants
    • Types of interventions
    • Types of outcome measures
  • Search methods for identification of studies
    • Databases you will use
    • Search terms you will use
  • Data collection and analysis

Note: elements may vary by discipline

"The preparation of a protocol is an essential component of the systematic review process; it ensures that a systematic review is carefully planned and that what is planned is explicitly documented before the review starts, thus promoting consistent conduct by the review team, accountability, research integrity, and transparency of the eventual completed review." - Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement

Eligibility criteria, also known as inclusion/exclusion criteria for a systematic review should be established before beginning your review. Eligibility criteria may include the types of studies most relevant for answering your research question. For clinical fields, you may also want to define the population you are looking at and include specifics in your eligibility criteria related to the population data.

Be sure that you have a clear, defensible reason for each criteria you include or exclude. While it may be tempting to limit by date or by peer review, this can introduce an element of bias into your methodology. Instead of including only peer reviewed articles, consider empirical studies as an eligibility criteria.

If you want to exclude older papers that may not be as relevant to your research question, document  defensible reasons for excluding papers written before a certain year.

Librarian tip: Review existing systematic reviews and protocols on topics similar to yours to see what types of eligibility criteria other authors are using. This can guide you in developing your own.