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Database Size and Shape (docz.dz) – Ovid MEDLINE

How to use the database command 'docz.dz.' and the Status (ST) field to identify the constituent parts of Ovid MEDLINE and show their relative sizes.

Ovid MEDLINE

Ovid Training Team

2024-07-15

92 visits

Background

This Focused Search establishes the number of records in the Ovid MEDLINE database as well as the status of those records at the time of the executed query. Database records enter the database via different routes. They move through a series of editorial processes and quality control checks and are only accorded MEDLINE status upon completion of those checks.

A record with MEDLINE status will have had MEDLINE’s proprietary medical subject heading terms, the so-called “MeSH terms” allocated to it. Knowing this has important consequences for how you build a search. Some 14% of the records in the database do not have MEDLINE status and so will not be captured using a search that only relies on MeSH thesaurus terms. Also, some limits, for example the Publication Type, Randomized Controlled Trial (randomized controlled trial.pt.) or Age Groups, All Adult (19 plus years) only operate on MEDLINE status records.

Noteworthy here is that the Status (ST) field, deployed as a limit, makes no mention of books. Books as a type of database record is accounted for by #7 in the search strategy, so that the number of records produced by lines #1 and #8 are the same. See below the attached reference Ovid's Medline Compared To PubMed (Ovid Knowledge Base) for details.  

The docz.dz Command
Entered at the command line in any of Ovid MEDLINE’s search modes, you can use the docz.dz command on any database on Ovid to establish the number of records in the resource. By combining this database command with database fields such as Status (ST) or Publication Type (PT), either individually or in combination, it becomes possible to imagine the ‘shape’ of the database. By this is meant the database’s structure, its composition in terms of database fields, its indexing processes, controlled vocabulary and limits options. These are database properties you need to know, be aware of  and consider when designing search strategies as they may have a material impact on your searches, their construction, execution and rendered outcomes.    

Practice Suggestions

  1. Calculate the percentage of PubMed-not-MEDLINE records currently on Ovid MEDLINE.
  2. Use the docz.dz command to establish the number of records in the other Ovid databases your institution has subscribed to, for example, Embase on Ovid, APA PsycInfo, Cochrane Database of Systematic Reviews (CDSR), Cochrane CENTRAL Register of Controlled Trials (CENTRAL), KSR Evidence etc.  
  3. Run the following docz.dz based search for Embase on Ovid. What does the result tell you about the ‘shape’ of Embase on Ovid? < Click here to run search >. Try also, 
  • APA PsycInfo < click here >
  • Food Science and Technology Abstracts < click here >
  • Cochrane Database of Systematic Reviews (CDSR) < click here >
  • Cochrane CENTRAL Register of Controlled Trials (CENTRAL) < click here >
  • KSR Evidence < click here >

    For each database list two aspects of the database's 'shape' that you had not known before. 

 

 

 

Search Stategy

docz.dz.

limit 1 to medline

limit 1 to "in data review"

limit 1 to in process

limit 1 to publisher

limit 1 to "pubmed not medline"

nb$.bk.

2 or 3 or 4 or 5 or 6 or 7

Launch Search

Reviewers

Primary: Michael Fanning

Secondary: Charlotte Viken

Review Date: 2024-07-15

Expiry Date: 2025-07-15

Original search produced by:

Ovid Training Team

Citation:

OvidGO! Portal. Focused Searches: Database Size and Shape (docz.dz) – Ovid MEDLINE [Internet]. London (UK): Ovid Training Team (Editors); 2024 [updated 25 October 2024; cited 30 October 2024]. Available from: https://tools.ovid.com/ovidgo/searches/view.php?id=50