Norwegian version of this page

Systematic literature search

If you are going to map the literature on a topic or write a systematic review, you need a systematic literature search. Depending on whether you are a researcher, PhD fellow, student, or employee, the library has different services to help you with searching.

Search help for students 

If you are a student at the University of Oslo, or an employee at Oslo University Hospital during your education, you can contact the digital library desk.

Digital library desk

Searches for systematic reviews and other evidence syntheses

In a systematic review, the literature search forms part of the data collection, and an experienced librarian can spend up to 30 working hours on such a search. It is therefore important to contact the library at an early stage in the project. During periods of high demand, some waiting time must be expected. Please note that this service is reserved for researchers and PhD fellows at the University of Oslo and Oslo University Hospital

Request a literature search for a systematic review or other evidence synthesis

A systematic literature search is a prerequisite for a systematic review and other evidence syntheses, in order to avoid bias.  At the University of Oslo there is a group of librarians who are experts in systematic literature searching. If you are a researcher or PhD fellow at Oslo University Hospital or the University of Oslo, one of our experts can assist in the following ways: 

  • Find out if a systematic review or other evidence synthesis on your topic already exists
  • In collaboration with you, translate your research question into a search strategy
  • Recommend bibliographic databases and other sources of information that should be searched
  • Guide or conduct systematic literature searches in relevant databases
  • Deliver the search result in a deduplicated EndNote library
  • Document the search strategy and write a description of the search for the methods section in your review
  • Update searches as needed
  • Follow recommended methods and standards

A clear question

In order to do a systematic search, you must start with a clear question. Also, the question should be broken down into elements that can be combined with OR and AND in a literature search. There are various frameworks that can help you clarify and structure your question. 

Frameworks to structure questions

A framework may help you structure the research question and break it down to elements that can be combined in the literature search. PICO (Population, Intervention, Comparison, Outcome) is widely used in medicine and health sciences, but is also often used in other disciplines. There are also other frameworks that may be better suited to your particular question. If your question does not fit into PICO or one of the other frameworks, don't panic, the most important thing is that you can break it down to at least two elements that can be combined in a search.

Learn more about PICO and other frameworks to structure your question.

Eligibility criteria

In addition to a clear question, you need to specify clear eligibility criteria. These are also called inclusion and exclusion criteria. The eligibility criteria should be specified in the protocol and be completely clear before the search is carried out and the search results are reviewed. PICO or other frameworks are also useful tools for specifying the inclusion criteria. In addition, an S is often added for which study designs are to be included. The eligibility criteria should not be changed on the basis of the studies you find. If during the review you decide to to add an inclusion criterion, it is crucial to do a new literature search which includes the new criterion to avoid bias.  

Study design

Different types of questions are answered with different types of study design. For example, a randomized controlled trial is the best study design to measure the effect of interventions, while cohort or case-control studies are suitable for finding answers to questions about etiology. More about study design.  

Which databases should be searched?

Depending on the subject area and topic for your review, the librarian will be able to suggest databases and adapt the search strategy to the various databases. You may also find information in the library's guide to databases and other information resources in your subject area

Description and documentation of the search

In a systematic review and other evidence syntheses, the literature search must be described and documented so that it can be replicated. This is necessary, among other things, for readers to be able to assess whether or not it is probable that all relevant studies were identified. The librarian who performs the search will document in detail which databases have been searched, how they were searched, the number of hits, and the date when the search was conducted. This documentation should be made available to the readers of the final article, e.g. in an appendix. The librarian can also write about the search in the method section of the article. This, in addition to reviewing the entire article, may qualify for co-authorship.

Published Dec. 9, 2021 9:37 AM - Last modified June 21, 2022 11:33 AM