How do I find and use free-text terms?

To find new articles that have not yet been indexed, or articles that have been indexed with other terms than those you’re using yourself, you should also search in the title, abstract and author’s keywords. This is usually referred to as a free-text search. It is recommended that you use the same search terms, both as controlled terms and as free-text terms

As free-text terms, you should include all the relevant synonyms and spelling variations that you can find in the key articles’ titles and abstracts. 

The databases’ thesauruses (the lists of the controlled terms) can be a helpful tool to use to find free-text terms, since these often list synonymous concepts. In PubMed, such synonyms are called Entry terms. Narrower controlled terms can also be included as free- text terms. 

Truncation

Use truncation to find different variants of a word. Therap* retrieves, for example:
•    therapy
•    therapies
•    therapeutic

Spelling variations in British and American English

Quite a few medical terms are spelled differently in British and American English. Consider whether or not your search terms include a word with a different spelling. If so, include both spellings. A few examples of different spellings in British vis-à-vis American English:
•    Tumour / Tumor
•    Gynaecology / Gynecology
•    Coeliac / Celiac
•    Ageing / Aging
•    Behaviour / Behavior

Searching for phrases 

Quotation marks are useful for keeping words in phrases together, but be careful when doing so during a systematic search. When you search for literature using quotation marks, the search becomes more precise; you will only find articles where that exact phrase is used and miss articles that contain variations on that phrase or a similar combination of search terms.  

Proximity operators

An alternative might be using proximity operators. These look a little different depending on which database you’re using:

NEAR in Web of Science and adj in Medline Ovid. 

Adding a number after NEAR/adj will determine how many words you want to “allow” between your two terms. This allows you to retrieve any variations on a phrase, for instance phrases that contain a different word order. 

For instance, if you did a search for “oxygen treatment” as a phrase in citation marks, you might miss any references containing phrases such as:

  • "oxygen (HBO) treatment"
  • "treatment with oxygen"
  • "oxygen in the treatment"

If you instead use a proximity operator (oxygen NEAR/3 treatment), your search will retrieve the variations.  

Senast uppdaterad: 2022-09-06