Deduplicating Search Results

Ovid's multifile (multi-database) search capability lets you search from multiple resources as though they were one. Ovid carries your query across all resources of the multifile (multi-database) and retrieves results from each. This doesn't apply to multimedia results, as duplicates are not loaded into the database.

The same record may be retrieved from more than one resource and appear multiple times in a results set. These duplicate records skew results and clutter your output. Ovid's deduplication feature allows you to eliminate duplicate records from either one of these two locations: the Search History Window or the Search Results Display.

The deduplication feature is only available for results sets that have less than 6,000 records. For larger sets, the deduplicate option is not available.

To view a YouTube video about deduplicating search results, click here.

Removing Duplicate Records

Select the Remove Duplicates option from one of these two locations:

Deduplicate link in the Search Information box
Deduplicate button in Search History

Ovid opens the Remove Duplicates page.

Select a set to deduplicate.
Edit field and/or database preferences.
Click the Continue button.

Ovid ranks results according to field, then database preferences chosen on this page. In our example, we set preferences for records that originate in the Embase database and has an abstract.

Results are posted to your Search History.

If Ovid does not find duplicate records in the results set, it displays "No duplicates were detected!" in the Search History.

Reviewing Duplicate Records

Even after Ovid deduplicates a set, you may review the duplicate records and make adjustments. Click the Review Duplicates button in your Search History.

Ovid opens the Review Duplicates page.

All the results from the original set are displayed here. Ovid groups pairs of duplicate records first. In addition, Ovid applies the field and database preferences that you indicated from the Remove Duplicates page. So, a field preference for records with abstracts results in preference being given to records that include an abstract. A database preference for Embase records results in preference given to Embase records over Ovid MEDLINE in the display.

Preferred and unique records are selected throughout. Eliminated records are displayed, but not selected. Use the record check boxes to revise selections. If you make changes, click the Keep Changes button to create a new results set in your Search History.

Maximum Set Size

The deduplication feature is only available for results sets that have less than 6,000 records. For larger sets, the deduplicate link is not available.

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

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