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Bull Med Libr Assoc. 1983 April; 71(2): 176–183.
PMCID: PMC227138

Indexing consistency in MEDLINE.


The quality of indexing of periodicals in a bibliographic data base cannot be measured directly, as there is no one "correct" way to index an item. However, consistency can be used to measure the reliability of indexing. To measure consistency in MEDLINE, 760 twice-indexed articles from 42 periodical issues were identified in the data base, and their indexing compared. Consistency, expressed as a percentage, was measured using Hooper's equation. Overall, checktags had the highest consistency. Medical Subject Headings (MeSH) and subheadings were applied more consistently to central concepts than to peripheral points. When subheadings were added to a main heading, consistency was lowered. "Floating" subheadings were more consistent than were attached subheadings. Indexing consistency was not affected by journal indexing priority, language, or length of the article. Terms from MeSH Tree Structure categories A, B, and D appeared more often than expected in the high-consistency articles; whereas terms from categories E, F, H, and N appeared more often than expected in the low-consistency articles. MEDLINE, with its excellent controlled vocabulary, exemplary quality control, and highly trained indexers, probably represents the state of the art in manually indexed data bases.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Meinert CL. Terminology--a plea for standardization. Control Clin Trials. 1980 Sep;1(2):97–99. [PubMed]
  • McCarthy SE, Maccabee SS, Freng CC. Evaluation of MEDLINE service by user survey. Bull Med Libr Assoc. 1974 Oct;62(4):367–373. [PMC free article] [PubMed]
  • Clinical disagreement: I. How often it occurs and why. Can Med Assoc J. 1980 Sep 20;123(6):499–504. [PMC free article] [PubMed]

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