MDSC1102: Literature review
Step 2: Finding your search terms
Now that we have established what our key concepts are we need to decide what terms (words or phrases) we are actually going to search for.
Where do you find alternative search terms for a concept?
Here are some alternative terms for our example research question.
Boolean operators are represented by the terms AND, OR. These terms are used between your search terms to tell the database how you wish to have them combined.
- All terms that describe the same concept (i.e are listed within the same column in the logic grid) should be linked with OR
- Concept groups should then be enclosed in brackets (see next tab) and combined with AND
It's not a bad idea to get into the habit of typing the Boolean operators in upper case: eg AND, OR. Some databases (eg. Informit, PubMed) don't work properly otherwise.
The truncation symbol (usually *) lets you find all words with the same word stem.
For example, Transplant* finds transplant, transplants, transplanted, transplantation.
Some advice about truncating:
- Apply at the end of a common word stem
- Take care not to cut a word too short
- For example: Hospit* finds hospital and hospitals but also hospitality and hospitable.
- PubMed truncation cuts out after 600 word variations. This sounds like rather a lot, however, therap* finds therapeutic and therapies but truncation cuts out before therapy.
- If this happens (you get a warning message) simply spell out the words in your search strategy rather than rely on truncation:
- i.e. therapies OR therapy OR therapeutic*
Example research question
Returning to our research question, the following terms could be truncated to improve retrieval:
- Smok* (for smoker, smokers, smoking)
- Tobacco user*
Brackets (or parentheses) are needed if you have both ORs and ANDs in the same search strategy. They go around a set of synonymous search terms where each term is combined using OR. This keeps a single concept search string out of the way of the AND.
For example, these search strings can be interpreted correctly by a database.
- Dogs AND cats
- (Dogs OR puppies) AND (cats OR kittens)
The following searches are not correct and won't be interpreted correctly by a database:
- Dogs OR puppies AND cats OR kittens
- Dogs OR (puppies AND cats) OR kittens
Our example research question
So how would we combine the terms from our example question? Each concept group here is shown in a different colour. Note the brackets around each concept group and the AND that separates them.
(Smok* OR tobacco user*) AND (electronic cigarette* OR e-cig* OR personal vaporiser* OR personal vaporizer* OR personal vapouriser* OR Electronic nicotine delivery system* OR ENDS) AND (quit smoking OR quitting smoking OR smoking cessation)