Searching

Testing searches

You should be creating and experimenting with several different versions of a search string before running your final search. You can use these trial searches as an opportunity to test your selection criteria as well.

To test that your searches are retrieving appropriate results, you can try these two methods: Sentinel Articles and the NOT operator.

Using sentinel articles

When developing your review topic, you likely came across a few articles that fit your selection criteria. You can use them to test your search, as these are articles that you should expect your systematic search to retrieve.

These are called sentinel articles, and you can build a search that retrieves only these articles by using the articles’ unique identifiers. For example, articles in PubMed have a unique identifier called the PMID. You can build a search consisting of only PMIDs by searching the PMIDs like this: PMID search for 31319564 OR 31226349 OR 34523250.

To test your search, use the database Search History to combine your systematic search and your sentinel article search with AND. The combined search will show you the number of articles common to both searches. If your combined search contains fewer records than your sentinel search, it means that not all of your sentinel articles are being retrieved by your current systematic search.

To determine which sentinel articles are missing, return to the database’s Search History and combine your sentinel search with your systematic search using NOT (so, Sentinel NOT YourSystematicSearch). Once you know which articles are not being retrieved by your systematic search, you can examine their records to determine why they were not being retrieved and make modifications to your search strategy as needed.

Using the search operator "NOT"

As you create your search, you may try different versions of your search using different parameters. For example, you may try limiting your keywords to the title/abstract field and try searching them in All Fields. You may try using truncation with a search term and you may just brainstorm the relevant terms with no truncation.

To test these searches against each other, you can use the NOT operator to see the differences between the searches. For example, you could have a first search that is very broad because you searched all your keywords as an All Fields search and you want to try to narrow it by searching your keywords only in the Title and Abstract fields. Run both of those searches, and then from the database’s Search History page, use the NOT operator to combine the searches: Search 1 (All Fields) NOT Search 2 (Title/Abstract). This will show you all the records that will be removed from your search if you make the changes to your search. Look at the records - are they relevant to your topic? If they are, perhaps you do not want to make these changes.