Limits and filters

You can apply limits and filters to ensure that you have fewer irrelevant results to look through.

Most databases offer the ability to refine your search results using different parameters:

  • Publication date
    The most commonly used limit is publication date – you can limit your search results to articles published in a particular year range. However, it’s important to remember that older papers may still be valid and relevant.
  • Geographical area
    Some databases allow you to limit by geographical area (for databases which use subject headings, there are usually geographical subject headings which you may wish to use). However, bear in mind that you may exclude some relevant articles when you limit by geographical area.
  • Language
    Most databases also allow you to limit your results to publications in a particular language, or languages. Whilst this may be useful, it’s not best practice if you wish to carry out a comprehensive search. There may be an abstract in a more commonly used language available which should give useful information about the content of the paper.
  • Publication type
    You can also restrict to certain publication types such as journal article, conference paper, randomised controlled trial, meta-analysis or review.
  • Search filters
    Some databases allow you to apply search filters (also called methodology filters) to your search. Search filters are pre-created search strategies which can be used to retrieve particular types of study, such as systematic reviews or meta–analyses. You can use the help pages of databases to find out which filters are available in that database. For example, CABI has produced a search filter to retrieve systematic reviews or meta-analyses in CAB Abstracts and Global Health called CABI filters.