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United States National Library of Medicine National Institutes of Health

Statistical Reports on MEDLINE®/PubMed® Baseline Data

NLM is pleased to provide a series of statistical reports run on baseline MEDLINE/PubMed data. The reports are available as both PDF and Microsoft Excel files and the overall report on the 2004 baseline is also available in HTML format. NLM expects to make similar reports available after the conclusion of each production year.

Baseline Description
The 2004 baseline database was produced in November 2003 at the conclusion of the 2003 MEDLINE production year and after NLM performed its annual data maintenance, primarily to apply the 2004 MeSH Vocabulary to the MEDLINE records. The statistics do not cover new, revised, or deleted records during the 2004 production year.

The baseline database includes all MEDLINE records (designated as MedlineCitation Status=Completed in the XML) as well as all records in PubMed-not-MEDLINE status (designated as MedlineCitation Status= PubMed-not-MEDLINE in the XML) at the time the baseline was created. It does not include the non-MEDLINE in-process status or in-data-review status records that NLM also distributes to MEDLINE licensees; nor does it include the publisher status records that reside in PubMed which are not distributed to licensees.

Documentation
An alphabetical list of the XML elements in the baseline database is at http://www.nlm.nih.gov/bsd/licensee/elements_alphabetical.html. Element documentation, including current definitions of the MedlineCitation Status attribute values, is available at http://www.nlm.nih.gov/bsd/licensee/data_elements_doc.html#elements.(Note that the xml elements change over time and some element names or values present in these baseline files may not be currently in use).

The Reports

  1. 2004 Baseline
    1. 2004 Overall Report
      The 2004 baseline contains 12,421,396 records. This report lists each element in the baseline and contains the following statistics:
      • total citations containing each element
      • total occurrences of each element
      • minimum/average/maximum occurrences of each element in a record
      • minimum/average/maximum length of a single element occurrence
      • average record size
      • average number words in title
      • average number words in abstract
      • number of abstracts with varying byte sizes
      • number of MeSH headings with no, 1, or more than 1 subheading
      • collective name counts
      • status counts
      • owner counts

    2. Baseline Auxiliary Reports
      The 2004 baseline report includes seven auxiliary reports for seven groupings of publication years (PubDate element). Each auxiliary report contains the same categories of data in the overall report for the following groupings of publication years:
      • 2000-2004
      • 1995-1999
      • 1990-1994
      • 1985-1989
      • 1980-1984
      • 1975-1979
      • pre-1975

    3. Publication Year Report
      A separate report run on the 2004 baseline database shows the total number of records in each publication year (PubDate element).

  2. Previous Baselines
    Overall reports are also available for baselines created prior to that for 2004. Auxiliary reports and publication year reports as done for the 2004 baseline are not available.

    Note that the various averages in all overall and auxiliary reports were computed via the following: Total number of Occurrences for an element / Total number of Citations that the element was found in

    The available reports are:

    Report Format
    2004 Baseline
    (includes auxiliary reports)
    63.77 KB PDF or 107 KB Excel or HTML
    (auxiliary reports not in HTML)
    2004 Publication Year 2.81 KB PDF or 14.0 KB Excel
    2003 Baseline 9.05 KB PDF or 26.5 KB Excel
    2002 Baseline 9.01 KB PDF or 26.5 KB Excel

Note: viewers for Microsoft® Office Products can be downloaded from http://office.microsoft.com/officeupdate/category.aspx?CategoryID=CD010225551033&CTT=98.
Note: PDF documents require the use of the Adobe® Acrobat® Reader, which can be downloaded from the Adobe's Web site at no charge.

Acknowledgement
These statistical reports were compiled by the Lister Hill National Center for Biomedical Communications of the Library, are freely available for use, and may be reproduced with attribution to the U.S. National Library of Medicine, Department of Health and Human Services using this citation: Statistical reports on MEDLINE®/PubMed® baseline data [Internet]. Bethesda (MD): National Library of Medicine (US), Bibliographic Services Division; 2004 Sep 30 [updated 2004 Oct 1]. [about 3 screens]. Available from: http://www.nlm.nih.gov/bsd/licensee/med_baseline_statistics.html


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First published: 30 September 2004
Last updated: 09 February 2005
Date Archived: 12 April 2007
Metadata | Permanence level: Permanent: Dynamic Content