A search filter is a search strategy also known as a search hedge, that has been developed to define certain criteria for your search. Many databases feature a built-in set of search filters that are commonly used to limit search results by age group, publication type, study type, and more. The Centre for Reviews and Dissemination has a list of published filters along with information on appraisal of search filters, links to articles that have evaluated filters, etc. When selecting a filter, be sure to look at the date of development as changes to database terms and structure can affect the performance of the search filter.
When conducting a systematic review, however, there is a possibility that these filters may exclude relevant studies. For this reason, search experts and institutions have developed their own search filters, and many are available online for public use. This guide will show some examples from various databases.
A well-designed search filter will very deliberately return extremely comprehensive results. We want -- if there is any possibility an article is describing some kind of whatever it is that filter is trying to find, that citation should be returned in the search. Ideally, a search filter should approach 100% sensitivity.
To use the search filter, run your search as you normally do in the database of your choice. After you are done combining your terms, find the filter based on the database you are searching and the research methodology you want. Copy the search filter and paste it into the search text box. Run the search, then use to combine it with your search.
There are several factors to consider when choosing a search filter.