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Systematic Reviews: Advanced Search Techniques

Advanced Searching

Database searching video

Search Operators

Search operators are special characters and commands (sometimes called “advanced operators”) that enable you to improve your search strategies. Using search operators you can improve the precision and relevance of the results you find.

Example Search Strategy

There is an example search strategy in the pdf below, which has been taken from a Cochrane Systematic Review entitled Dance movement therapy for dementia.

The strategy is also available to view in the systematic review appendices, available here:

Additional Search Strategies

Subject Headings/Thesaurus

Subject Headings are standardised terms:

  • Fixed list of terms arranged hierarchically with broader and narrower terms.

Assigned by expert indexers (humans not machines!):

  • Indexers classify the article by tagging it with subject headings that relate to the content.
  • Some tags represent the main focus of the article and some refer to secondary aspects of the work.

Allows exploration of associated (broader, narrower and related) terms in subject tree:

  • Can allow you to search more effectively and avoid missing relevant articles.

Can help your search and avoid problems inherent in free text searching:

  • Can retrieve relevant articles where the term does not occur in title or abstract.

Not all databases provide subject headings or a thesaurus (e.g. Scopus and Web of Science do not):

  • In these databases you need to rely on just keyword searching, ensuring that you use as many synonyms, and alternate terms as possible.

Different databases use different subject heading thesauruses (Medline uses MeSH, etc):

  • This means that you cannot use the same subject headings from one database in another but will need to research for each concept in order to locate the relevant subject heading (if it exists) and add that to your search.

Remember to check ‘Scope’ notes that explain the Subject Headings and explore the subject tree where you can explode or focus terms:

  • Choosing the explode option automatically includes your Subject Heading and any of the Narrower Terms below that heading 

Search in stages (one concept at a time) and then combine results using Search History functions:

  • Ensure you are breaking your search concepts down and combining with AND or OR