Search filter

A search filter is a ready-made search strategy designed to limit search results to a set of references with specific characteristics. Filters are usually combined with a topic by using ‘AND’, in order to restrict the search to a smaller, more relevant set of results. Other Boolean operators, such as ‘OR’ and ‘NOT’ may be used. For example a randomised controlled trial (RCT) filter should retrieve only those studies that are RCTs. Several versions of a filter may exist depending on how exhaustive or precise they aim to be. Well-designed filters will retrieve all relevant studies while reducing the amount of literature that needs to be screened by reviewers.