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Postgraduate Medicine: How to Search the Literature

This guide offers an eight step approach from identifying your topic to managing your search strategy and results.

6. Search a Database

The following steps to searching a database have been tailored for Ovid Medline. However, this is a general approach and it can be applied to different databases.

Steps

1. Search for each concept and their search terms one at a time.

  • Entering each term one at a time will help to ensure that the appropriate subject heading is identified.
  • Some databases (e.g. Ovid Medline, Ovid Embase, CINAHL) will automatically map your term to a list of potential subject headings.

e.g. OVID Medline Epub Ahead of Print, In-Process & Other Non-Indexed Citations, Ovid MEDLINE(R) Daily and Ovid MEDLINE(R) 1946 to Present

The following screen will be displayed after clicking on Search:


 

2. Click on the Scope Note to determine if a subject heading is relevant. Click on Previous Page to return to the Mapping display screen.


 

3. You may optionally Explode or Focus a subject heading. Clicking on a subject heading from the Mapping display screen (see above) will display the following:
 


Explode
 can potentially increase the number of results by retrieving records that include the selected subject heading as well as narrower subject headings (listed directly below it and indented to the right). In the example above, Tennis elbow does not have narrower subject headings. However, it is a narrower subject heading of Elbow Tendinopathy

Focus will decrease the number of results by retrieving records where that subject heading is considered to be the main theme. It should be used with caution, and is rarely used in a comprehensive search strategy

Once a subject heading like Tennis Elbow has been selected, you can further narrow the search results by attaching a subheading to it.

Subheadings are used to describe the specific aspects of the subject heading that are pertinent to the item. They should be used with caution when constructing a complex search strategy because they are subjective. In certain circumstances, they can be used as an additional search strategy.

  • For example, a search for Tennis Elbow/su [Surgery] will retrieve results where Tennis Elbow is the subject heading and surgery is its subheading.
     

4. Search for all of the terms within your first concept (e.g. Tennis elbow) using a combination of subject headings and keywords; then combine them using the OR Boolean operator.

  • Remember to incorporate truncation and wildcards for keyword searches where appropriate


 

5. Search for all of the terms within your second concept (e.g. surgery) using a combination of subject headings and keywords; then combine them using the OR Boolean operator.

Note: Combining terms within a concept in an Ovid database can be done in multiple ways; see lines 5 and 10
 

6. Combine the final search set for each of the concepts using the AND Boolean operator. For example, combine lines 5 with 10 using the AND Boolean operator (i.e. 5 AND 10).
 

7. If appropriate, search for a subject heading and its relevant subheading to supplement your final search result (see line 10 in the above example). Combine these results using the OR Boolean operator (see line 13 in the example below) .

Note: In the above search history, .mp. indicates a keyword search while a forward slash [/] indicates a subject heading search.
 

8. Apply limits one at a time to see how each narrows the results.

  • Limits can be informed by your inclusion and exclusion criteria
  • Use limits at the end of your search to determine its effectiveness
  • Limits can vary from one database to the next


 

9. Test your search strategy.

  • Check to see if your set of "known" articles on your topic are included in your search results
    • Search by the title of the article, and then OR the result to your final search set. If the result does not increase then it has been captured by your search strategy. If it was not captured, then look at the article's Complete Record to see how the article was indexed and the terms used by the author(s). Revise your search strategy accordingly.
  • Run your search strategy by your advisors and/or research team for feedback
  • Ask a librarian to review your strategy
     

10. Save your search strategy.

  • Most databases will allow you to create an account to save your search strategy, which will allow you to modify it at a later date, share with colleagues or create an auto alert when new items have been added to the database.
     

11. Replicate your search strategy in other databases. A search strategy designed for one database will need to be "translated" for use in other databases, because:

  • Controlled vocabulary / subject heading terms vary across databases
    • E.g. Medline uses MeSH while Embase uses Emtree
  • Commands, operators, limiting options, and availability of search fields will differ between databases

Remember that searching is an iterative process, and if you find a unique term in a subsequent search then you should revise your initial search.

See next page, Translating a Search Strategy, for more details.