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Literature searching: Using limits in your search

Be careful about using 'limits' in your searches

Some databases, such as Ovid MEDLINE(R) ALL, include many thousands of non-indexed records and pre-print publications. These new records flood in from electronic publications and there is a time lag before they can be fully indexed or described. The records received from publishers are basic and don't (yet) include subject headings. Of course these non-indexed records include the latest research, so we don't want to lose them.

  • They do not include subject headings - so we have to use text word searches to find them
  • They do not include indexing for human or animal studies - so we lose ALL of the non-indexed records if we 'limit to humans'.
  • They do not include indexing for age ranges or gender or most other automated limits - so we lose ALL of the non-indexed records if we use those limits

There are the only two limits we recommend:

  • English language - works for most old and new records. However some records from the 1980s and 1990s don't index language at all. 
  • date range - these are publication dates included in the basic record

How to exclude animal studies

Don't 'limit to humans'

If you select 'limit to humans' you risk losing all non-indexed and pre-print publications in a database which have not been indexed as 'human'. This could be thousands of records.

Instead, remove the animal studies

A safer alternative is to search for the things we don't want (in this case animal studies) and remove them from the results. Adjust the line numbers below as appropriate.

Ovid Medline

6. [last line of search - your line number will be different]
7. exp animals/ not humans/ 
8. 6 not 7

Ovid Embase and Ovid Emcare

6. [last line of search - your line number will be different]
7. exp animal/ not human/ 
8. 6 not 7

APA PsycINFO  (Ovid)

6. [last line of search - your line number will be different]
7. (animal not human).po. 
8. 6 not 7

CINAHL (EBSCOhost)

S6. [last line of search - your line number will be different]
S7. (MH "Animals+") NOT (MH "Human") 
S8. S6 NOT S7