Learning and Teaching: Advanced Literature Search Guide for Health: STEP 6: Refine results

Search limits should be applied at the end of your search after you have retrieved all the results relevant to your topic. Apply limits one at a time so you can see what effect they have on your results.
Most databases allow you to limit your searches by publication date, language, and publication type. Each database offers a different range of limits e.g. Cinahl offers language, age range etc.

Using too many limits may narrow your search too far; for this reason you could consider using search filters as an alternative. Search filters are pre-tested strategies that identify the higher quality evidence from the vast amounts of literature indexed in the major medical databases.

If you find too few results consider the following:

Check your spelling
Has anything actually been written on your chosen topic?
Have you used Boolean operators correctly.
Avoid the use of fixed phrase searching e.g. "health education"
Do you need to search more databases? Are you searching the most appropriate databases?
Could you add more search terms to your search strategy? Are there any more synonyms or alternative words you could use to broaden your search - look at your initial search results for ideas.
Are your date limits too restrictive?
Remove the least well defined concept string (this usually relates to outcomes).

Is the search question too broad, do you need to develop it further?
Have you used Boolean operators AND OR NOT correctly?
Re-run your main search string as words in title - this is usually the string which describes your intervention or exposure.
Remove truncation and search on the most commonly used variant of the word.
Add an extra search string for any concepts you have not already included in your search (e.g. for your outcomes string which is often omitted because of the difficulty in pinning it down).

For more information about refining and improving your search results, take a look at the documents below.