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Embase on Ovid – Limiting Searches To Time Spans (Date Range Searching)

How to limit searches to spans of time from complete years or parts of years to user-defined time frames covering years, weeks or days.

Embase

Ovid Training Team

2025-03-12

34 visits

Background

Embase, produced by the academic publishing and information analytics company Elsevier B.V., is one of the largest and most comprehensive Abstracting and Indexing (A&I) database for peer-reviewed biomedical information. The Embase database covers all disciplines of medical and biomedical science as well as Allied Health subjects.

Embase on Ovid – Facts and Figures (1)

  • A bibliographic database, Embase is made up of over 41 million database records.
  • Over 1.7 million records are added each year.
  • Database records are indexed using Emtree, the Elsevier Life Science Thesaurus.
  • Conference materials, currently at over 5 million records, have been included since 2009.
  • Preprint records, from several sources, have been included since November 2021.
  • All database records are indexed using automated means and procedures.
  • Records pertaining to diseases, drugs and devices undergo further manual indexing.

Training Session Programme

This Learning Pathway series of training modules draws upon the content and teaching approaches in and behind the learning resource OvidGO! (2). Constructed around a selection of focused searches, the training programme has been designed to achieve the following two objectives,

  1. to introduce the database, Embase on Ovid, drawing upon where helpful, parallels and comparisons with Ovid MEDLINE,
  2. to discuss, demonstrate and practice the key features and functionality of the database Embase on Ovid. 

(1) Reference for the above is the Embase Indexing Guide 2024.
(2). See https://tools.ovid.com/ovidgo/       

This Focused Search looks at ways in which searches can be limited to general or specific spans of time.

Limiting by a Range of Complete Years
The easiest way to limit a search to a range of complete years is to use the Year of Publication (YR) field. This field is marked and populated by the indexers as soon as the processing of the original document begins.  The database’s Limits function provides the option for the user to enter the wished for date range. Alternatively, set ranges, i.e. 3 Years, 5 years etc. can also be selected. All the records in Embase on Ovid have a year of publication. See lines #1 and #2 of the accpmpanying Focused Search. But note this is distinct from the dates connected to the document’s record being processed for inclusion in the database.

Limiting by Parts of Years
For searches across parts of years, down to months and even days, Ovid recommends using the First Date (DD) (formerly the Date Delivered field) field. This field marks the date when the document’s record was added to Embase. As the date reflects the date on which the citation was added to the database, this is not the date of either the original document’s publication or even its electronic publication in the database. Also as a phrased-indexed field (compare lines #6 and #7 in the accompanying Focused Search), the First Date (DD) field lends itself well to truncation. So for example in the expression limit 1 to dd=202401*-202402* will yield results from all of January 2024 to all of February 2024.

Updating Search Strategies
Search strategies can be updated using the date range searching methods as described above. However, due to the inherent dynamism within the database’s records management, care must be taken when interpreting the results. An alternative method is to extract the records, on say day x and save them according to their unique identifiers (which in Embase is the record's Accession Number (AN)), either as a search in My Workspace or in an external document. Then later, on day y, run the same search and save these results similarly. Use the NOT operator to establish the difference between the results sets for day x and day y. This final result will indicate the number of records additionally found between day x and day y.

Practice Suggestions

  1. How many records are there in Embase on Ovid whose publication date is in the 1800s? Is this the same for a similar search in Ovid MEDLINE? 
  2. Is the last record in Embase on Ovid the oldest record in the database? Is the last record available in full text? How could you establish this?
  3. How could you use date range searching to illustrate the rapid rise of articles in Embase on Ovid that discuss the role of ChatGPT in health care?

Search Stategy

docz.dz.
(19* or 20*).yr.
"2024".yr.
("2020" or "2021" or "2022" or "2023" or "2024" or "2025").yr.
limit 1 to yr=2020-2025
"2024".dd.
2024*.dd.
limit 1 to dd=20250101-20250331 [Date Range: 1st January 2025 to 31st March 2025]
limit 1 to dd=20240101-20240331 [Date Range: 1st January 2024 to 31st March 2024]
limit 1 to dd=20240601-20240610 [Date Range: 1st June 2024 to 10th June 2024]

Launch Search

Reviewers

Primary: Michael Fanning

Secondary: Charlotte Viken

Review Date: 2025-03-12

Expiry Date: 2026-03-10

Original search produced by:

Ovid Training Team

Citation:

OvidGO! Portal. Focused Searches: Embase on Ovid – Limiting Searches To Time Spans (Date Range Searching) [Internet]. London (UK): Ovid Training Team (Editors); 2025 [updated 2 March 2025; cited 10 March 2025]. Available from: https://tools.ovid.com/ovidgo/searches/view.php?id=107