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Systematic Reviews : Searching

A brief guide on how to conduct a systematic review.

Tips for searching

Evaluating the quality of your search strategies by using the PRESS checklist:

  1. Is the search question translated well into search concepts?
  2. Are there any mistakes in the use of Boolean or proximity operators?
  3. Are any important subject headings (i.e. controlled vocabulary terms) missing or have any irrelevant ones been included?
  4. Are any natural language terms or spelling variants missing, or have any irrelevant ones been included? Is truncation used optimally?
  5. Does the search strategy have any spelling mistakes, system syntax errors, or wrong line numbers?
  6. Do any of the limits used seem unwarranted or are any potentially helpful limits missing?
  7. Has the search strategy been adapted for each database to be searched?

McGowan J, Sampson M, Salzwedel DM, Cogo E, Foerster V, Lefebvre C. PRESS Peer Review of Electronic Search Strategies: 2015 guideline statement. J Clin Epidemiol. 2016 Jul;75:40-6.

Choosing databases

When it comes to choosing a database, we recommend 5 broad databases


However, your database selection will be dependent on your faculty/subject area, so, consult your database suggestions on your subject libguides.


Constructing a search string

Developing a search strategy, ensure that you

  • Check and use the controlled vocabulary for each database; it may not be called MeSH. 
  • Adapt search syntax (field tags, phrase searching, etc.) for each database.
  • Check whether proximity operators are available and will help with natural language searching

Steps required when developing a  search strategy for a systematic review:

  1. Formulate the research question
  2. Identify the key concepts
  3. Develop search terms - synonyms
  4. Search fields
  5. Use Boolean operators, phrase searching, wildcards, proximity operators
  6. Consider search limits

Boolean operators 

Most of our databases, including the library catalogue take Boolean operators. Boolean operators allow you to combine keywords for a search.

Diagram Explaining Boolean Operators

For example,

"(child* OR wom?n OR gender) AND poverty AND Africa* NOT African American

The (brackets) keep the OR words together and relate them to the AND which follows 

“Inverted commas” enclose a precise phrase.

(child* OR wom?n OR gender)

  • The * is a wildcard – it calls up anything that follows the root “child” – so it will being up child and children or childhood
  • The OR expands you options – women or gender must come up in the results
  • The ? is a mid-word wildcard – calls up women and woman

Poverty AND Africa* NOT “African American”

  • Will only give you articles that speak about poverty and Africa together and will not give you any articles that mention African American 
  • NOT excludes a term. Be careful of this. First search without it, to get an idea of what you are missing.


The PICO framework focuses on the Population, Intervention, Comparison and Outcomes and it is a commonly used tool in systematic reviews to identify different components of clinical evidence for a systematic review, and the Cochrane Collaboration recognizes it. There are various iterations of PICO. Please note that not every systematic review question lends itself to the PICO framework.


Population/ Problem Population Population
Intervention/ Exposure Intervention Intervention
Comparison Comparison Evaluation
Outcomes Outcomes  
  Time frame  
  Study Design