Ovid Mapping

Ovid's mapping process utilizes statistical analysis to match a search term with the controlled vocabulary of a database. Mapping is a keyword command line tool enabled by default in databases that have a controlled vocabulary (a set of pre-determined terms describing concepts within the database). A controlled vocabulary indexes variants under industry-established terminology. By mapping your search terms to a database's controlled vocabulary, Ovid eliminates a lot of guess work from the development of search strategies.

In mapping-enabled databases, a Map Term to Subject Heading check box displays below the keyword command line.

To view a YouTube video about mapping and controlled vocabulary, click here.

Keyword Command Line

Ovid does not apply mapping when you use command line syntax to run a search from the Main Search Page.

Mapping functionality is not available in the Books@Ovid database, nor is it available in multifile (multi-database) sessions.

Enter a search term that maps to subject headings (the indexed terms of a controlled vocabulary), Ovid will open the Mapping Display and list the best-matching subject headings associated with your term. For example, search for the term heart attack in Ovid MEDLINE, and Ovid maps to the subject headings associated with myocardial infarction and opens the Mapping Display that lists them.

Mapping Display for Heart Attack

On the Mapping Display window, subject headings are hyperlinked to a structured vocabulary tool such as a Tree, Thesaurus, or Permuted Index. Click the subject heading link and Ovid opens the structured vocabulary display, highlighting the subject heading within the context of the tool. Viewing a subject heading within the vocabulary tool can help you decide if you want to Explode (for broader results) or Focus (for topic-specific results) on the term for best results.

In this example, Ovid has mapped our search terms to one subject heading.

Click Information icons to view scope note information about the subject headings, including: definition, date of entry into the controlled vocabulary of the database, and used-for terms (a history of prior indexing of the term).

To gain results quickly from the Mapping Display:

Select the checkboxes of subject heading terms to include in your search.
Select the Include All Subheadings check box.
Choose a Boolean operator from the pull-down menu.
OR: Retrieves results that contain at least one of the selected subject headings.
AND: Retrieves only those results that contain all selected subject headings.
Click the Continue button.

Ovid will post the results to the search history back on the Main Search page.

Select the Search as Keyword check box from the Mapping Display and click the Continue button if your initial search term does not map to a subject heading of interest to you. Ovid runs a standard keyword search and posts results to your search history back on the Main Search page.

Un-check the Map Term to Subject Heading box located above the Search button on the Main Search page to disable Mapping. Ovid then performs keyword searches through field defaults of the database(s). Refer to the database field guide for information about the availability of Mapping and database default fields.

You can map a known subject heading directly from the Main Search page's keyword command line by typing <subject heading term>/, as in the command myocardial infarction/.

Explode a Term from the Mapping Display

Exploding a subject heading from the Mapping Display lets you retrieve results that contain the subject heading in combination with all of its narrower, more specific subheadings. Subheadings provide a broader scope of interpretation for the subject heading.

Selecting to Explode myocardial infarction

In this example, we want to explode the mapped subject heading myocardial infarction from the Mapping Display:

Select the check box of the subject heading myocardial infarction.>
Select the subject heading's Explode check box.
Select the Include All Subheadings check box.
Click the Continue button.

Ovid displays your results in the search history of the Main Search page.

In the statement displayed in your search history, exp indicates that the term has been exploded.

In databases with a controlled vocabulary, use the exp command to explode a known subject heading directly from the keyword command line. For example, the command exp myocardial infarction retrieves records that contain the term myocardial infarction and all of its subheadings.

Exploded results represent the number of records that contain the subject heading term, whether it is the main topic of the article or if it appears in combination with any of its subheadings. Therefore, you gain the most comprehensive results when you explode a subject heading.

If you do not want all subheadings to be included within exploded results, you may select only those that imply the meaning of the subject heading that you want. To gain such selective results from exploding a subject heading, follow the same steps from the Mapping Display.

Select the checkbox of the subject heading term you want to explode, in this example: myocardial infarction.
Select the term's Explode check box.
Unselect the Include All Subheadings check box.
Click the Continue button. Ovid opens the Subheadings Display for that term.
Subheading Display for myocardial infarction
From the Subheading Display, select subheadings associated with the meaning of the subject heading you want in your results.
Choose a Boolean operator from the pull-down menu.
OR Retrieves results that contain any one of the subject headings selected.
AND Retrieves results that contain all subject headings selected.
For this example, we have selected the subheadings Blood and Metabolism.
Click the Continue button.

Ovid posts results in the search history back on the Main Search page.

Results from Exploding myocardial infarction and Applying Two Subheadings

Notice that fewer results display back in the search history of the Main Search page from having refined the subject heading myocardial infarction to only that subheading (aspects of the subject heading) of interest to you.

Database publishers index records using the most specific terms of their industry. To ensure that your search gains comprehensive results, explode subject headings to include all related subheadings.

Use the command sh <term> to open the Subheading Display for a known subject heading. For example, the command sh myocardial infarction displays the list of subheadings for the term myocardial infarction.

Focus a Term from the Mapping Display

Ovid retrieves results in which your subject heading is considered the major topic when you focus on a subject heading term from the Mapping Display.

Selecting to Focus from Mapping Display

From the Mapping Display, we want to focus the subject heading myocardial infarction.

Select the check box of the subject heading myocardial infarction.
Select the subject heading's Focus check box.
Select the Include All Subheadings check box.
Click the Continue button.

Ovid displays results in the search history on the Main Search page.

In the statement displayed in your search history, the * symbol that precedes the search statement indicates that the term has been focused.

In databases with a controlled vocabulary, use the *<subject heading> command to focus a known subject heading directly from the keyword command line. For example, the command *myocardial infarction refines results to only those for which the term myocardial infarction is the main topic.

These results represent the number of records for which the subject heading is the major topic. Note the difference between the exploded and focused results gathered so far.

If you do not want to include all of the subheadings within your focused results, you may select only those that better refine the meaning of the subject heading toward results that you want. To gain such selective results from focusing a subject heading, follow the same steps from the Mapping Display.

Select the check box of the subject heading myocardial infarction.
Select the subject heading's Focus check box.
Unselect the Include All Subheadings check box.
Click the Continue button. Ovid opens the Subheadings Display for that term.
Subheading Display for Myocardial Infarction
From the Subheading Display, select subheadings associated with the meaning of the subject heading you want in your results.
Choose a Boolean operator from the pull-down menu.
OR Retrieves results that contain any one of the subject headings selected.
AND Retrieves records that contain all of subject headings selected.
For this example, we have selected the subheadings Blood and Metabolism.
Click the Continue button.

Ovid posts results in the search history on the Main Search page.

Notice that Ovid retrieved fewer records as a result of refining the subject heading topic search to only those subheadings (aspects of the subject heading) of interests to you. Use Ovid's Focus function when you want to retrieve the most specific information for your search.

Vocabulary tools like the database Tree, Thesaurus, Permuted Index, and Classification Codes allow you to utilize Ovid's Explode and Focus functionalities.

Use the command sh <term> to open the Subheading Display for a known subject heading. For example, the command sh myocardial infarction displays the list of subheadings for the subject heading myocardial problems.

Select the Search as Keyword check box and click the Continue button if your search term does not map to a subject heading which interests you. Ovid runs a keyword search for your term in the default fields of the database.

For more support information and training content, please visit the
Ovid Tools & Resources Portal.

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OR:	Retrieves results that contain at least one of the selected subject headings.
AND:	Retrieves only those results that contain all selected subject headings.

OR	Retrieves results that contain any one of the subject headings selected.
AND	Retrieves results that contain all subject headings selected.

OR	Retrieves results that contain any one of the subject headings selected.
AND	Retrieves records that contain all of subject headings selected.