Many databases provide system based limits. Adding a limit to a search will exclude certain material not relevant to your research question, and therefore reduce the number of results. These functions vary from database to database but often appear on your initial search screen or beside your search results.
Examples include limiting:
- to English language
- by publication date
- to a specific document type
- your search to specific fields, such as only searching in the Title/Abstract fields
Limits should only be applied once your search strategy is complete. (Do not apply the same limit multiple times to different search lines).
The use of limits can result in the exclusion of relevant studies, so any use should be justified by the focus of your research and any constraints.
If conducting a systematic review for publication, always use a Search Filter in place of limits.