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  • 1. Google Scholar vs. MEDLINE for Health Sciences Literature Searching Patricia M. Weiss, MLIS Health Sciences Library System University of Pittsburgh March 19, 2008
  • 2. Copyright © 2008-2009 Health Sciences Library System, University of Pittsburgh
  • 3. About MEDLINE
    • Largest database of indexed journal citations for health sciences literature
      • Indexed records = Organized records that include standard descriptors of topics
    • >16 million citations from 5000 journals back to 1949
    • Produced by National Library of Medicine (NLM), one of the National Institutes of Health
  • 4. About MEDLINE
    • Available with different interfaces developed by different organizations
      • Interface = screen you see + search engine in background
    • HSLS supported versions
      • PubMed (from NLM)
      • Ovid MEDLINE (from Ovid Corporation)
    • Other versions (ClusterMed, Web of Science, EBSCOhost, etc.) look different but have the same raw data.
  • 5. PubMed
  • 6. Ovid MEDLINE
  • 7. MEDLINE Database
  • 8. Fields in a MEDLINE Record
  • 9. NLM’s PubMed Ovid MEDLINE
  • 10. Journals Included in MEDLINE
    • List of journals is easy to find and refer to.
    • Information about coverage is clearly stated.
  • 11.  
  • 12. MeSH ( Me dical S ubject H eadings)
    • MeSH = Organized hierarchical “tree” system of standardized terms used to index all articles
    • Articles on the same topic are indexed with the same term, even if authors use different terms for same concept.
    • As opposed to: Searching for a particular string of characters (“textword” or “keyword” searching)
  • 13.  
  • 14. Fields in a MEDLINE Record
  • 15. Different Terms, Same MeSH
    • Title #1
    • Treatment of
    • gastric cancer .
    Title #2 Technical considerations in laparoscopic resection of gastric neoplasms . MeSH headings for both titles : Stomach Neoplasms
  • 16. Same Term, Different MeSH
    • Title #1
    • The diagnosis of plaque - induced periodontal diseases.
    • MeSH heading:
    • Dental Plaque
    Title #2 Mechanism of senile plaque formation in Alzheimer disease. MeSH heading: Senile Plaques
  • 17. MEDLINE Strengths
    • You are searching the bulk of health sciences literature.
    • Easy to determine if a journal is included and how far back it goes
    • All articles from important journals are included.
    • Concept as well as textword searching
  • 18.  
  • 19. MEDLINE Limitations
    • MeSH has a learning curve, can be difficult to use well.
    • MeSH indexers aren’t infallible; indexing can be inconsistent.
    • MEDLINE record includes information about article but not full text of the article.
    • Search results are typically ranked by date, not relevance.
    • It takes time for articles to be processed and MeSH terms to be assigned.
  • 20. MEDLINE Limitations
    • New journals generally not included until they have proven themselves over several years
    • Includes primarily journals related to the health sciences and a few major journals from related disciplines
      • Does not include health-related articles from journals in other disciplines
  • 21.  
  • 22. About Google Scholar
    • Google “harvests” information from full-text articles with publisher permission, then makes them fully searchable.
      • Not all publishers are included.
    • Also includes books, free and “open source” resources, digital libraries, and other scholarly sources on the Web
    • 2 different types of entries
      • Main entries for publication itself
      • Mini-entries for cited references that GS cannot find online. [citation]
  • 23.  
  • 24.  
  • 25. From GS Help Anatomy of a Google Scholar Record
  • 26.
    • Full-text searching
      • Lets you search for specific details in the article itself (place, substance, personal names)
    • Relevancy ranking
    • Covers literature from many disciplines and from non-journal sources
      • Scopus and ISI Web of Science do this, too.
    GS does it, MEDLINE doesn’t:
  • 27. GS Limitations
    • No consistent format for journal titles –
      • Need to search on full title and maybe several possible abbreviations to find everything
    • Publication Date is not always captured and not always visible in the full text.
      • A search for documents published in 2005, would not retrieve 2005 items with no date listed.
  • 28. Scope of Google Scholar?????
    • MEDLINE: >16 million articles back to 1940s
    • GS: #??? articles back to 19##???
  • 29. GS Limitations: The Denominator Problem
    • Is database coverage well-documented?
      • If not, how do you know what you’re missing?
    • Is the database concept indexed with standardized terms?
      • If not, can you think of all the different text strings that might elicit retrieval?
      • (And if not, how do you know what you’re missing?)
  • 30. 2008 2007
  • 31. GS Limitations: Keyword Searching
    • No standardized terms for concepts You’re on your own with trying to think up all the different terms an author might use to evoke a particular context.
    • GS general vocabulary resource is Answers.com
      • MeSH developed by NLM
      • Stedman’s Medical Dictionary originally a main source
  • 32. Google Scholar Summary
    • Search results ranked by relevance
    • Links to citing references + secondary records for cited references not otherwise included
      • Export to EndNote, RefWorks is possible.
    • Number of records unknown
    • Journals plus books and other information types depending on institutional configuration
    • Coverage (which journals?) unknown
    • Multidisciplinary; subject area limits available
  • 33. Other Multidisciplinary Indexes: Scopus and Web of Science
    • Scopus (from Elsevier; 29 million abstracts, >15K journals, back to 1966; sciences + social sciences)
    • WoS’ Science Citation Index Expanded (from Thomson; >6,650 major journals as far back as 1900 in 150 scientific disciplines)
    • May include MEDLINE records, but no standardized terms of their own
    • Citing and cited reference lists
    • Easy export to EndNote, RefWorks
  • 34. Product Feature Comparison   Google Scholar MEDLINE (via PubMed) Web of Science Scopus Concept searching?    some Sources list (which journals, etc.)?     Cited reference list?     Citing reference list?     Export to EndNote, RefWorks?  manual import   Score 40% 50% 60% 90%
  • 35. Bottom Line: Both Tools are Useful
    • GS is weakly defined and lacks consistency but has features lacking in MEDLINE.
    • For serious researchers, GS is not a replacement for a MEDLINE search.
    • GS makes it easy to find some articles quickly.
    • As a multidisciplinary and multi-format resource, GS may present items not found in MEDLINE.
  • 36.
    • Pat Weiss
    • Phone 412.648.2040
    • [email_address]
    • Falk Library Reference Desk
    • Phone 412.648.8796
    • [email_address]