Creating a protocol
A systematic review requires a written protocol that specifies the plan which the review will follow to identify, appraise and collate evidence. The protocol makes the review process transparent and helps to avoid or minimise bias.
Components of a protocol
- Background information
- The research question
- Search strategy
- Study selection (inclusion and exclusion criteria - see information opposite)
Scoping searches
As part of your preparation of your protocol you will need to do some scoping searches. They will help you define the limits of your search and you can also use these searches to start identifying search terms to use later on in your search strategy.
Registering your protocol
If you are a a doctoral candidate and your review is health-care related, consider registering your final protocol on PROSPERO to publicise that you are doing this research. You can also check here that no one else is undertaking a systematic review on the same topic.
Next step: Location of Studies
Inclusion and exclusion criteria
Inclusion and exclusion criteria are decided in advance and included in the protocol. They are the criteria that decide which studies should be included in the systematic review analysis.
"The review protocol should provide explicit, unambiguous, inclusion criteria for the review."
The JBI Manual for Evidence Synthesis, 2020
Possible inclusion/exclusion criteria to consider
Date: Has there already been a systematic review in this area? Refer to this study and it's findings in your introduction and start your review AFTER that study.
Geographic location of study: you may only be interested in studies from a particular country, or countries that share demographic or economic factors.
Language: very few systematic reviews request translations of papers!
Participants: age group, gender, ethnicity etc…
Participant Experience: participants may need to meet a condition to be included (eg: received a particular diagnosis, prescribed a drug, taken a class)
Peer Review: Some systematic reviews will exclude non-peer reviewed literature, but many will include grey literature.
Setting: Where are the participants located? (School, hospital, prison)
Study Design: Randomised control trials, participation studies, longitudinal studies…
Type of Publication: usually looking for original studies, rather than editorials, reviews or letters
The Cochrane Handbook recommends:
"The population, intervention and comparison components of the question, with the additional specification of types of study that will be included, form the basis of the pre-specified eligibility criteria for the review."
Chapter 3 of the Cochrane Handbook has lots of advice on selecting your inclusion or eligibility criteria.