Google Scholar vs. MEDLINE for Health Sciences Literature Searching

Slide 1: Google Scholar vs. MEDLINE for Health Sciences Literature Searching Patricia M. Weiss, MLIS Health Sciences Library System University of Pittsburgh March 19, 2008

Slide 2: 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

Slide 3: 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.

Slide 4: PubMed

Slide 5: Ovid MEDLINE

Slide 6: FIELDS RECORDS (information categories) Author Title Journal Publication Year Gualandi- Insulin formulations--a review European Review for Medical & 2001 Signorini AM Pharmacological Sciences Bremseth Delivery of insulin by jet Diabetes Technology & 2001 DL, Pass F injection: recent Therapeutics observations Zahn H My journey from wool Journal of Peptide Science 2000 research to insulin Ionescu- Insulin, the molecule of the Archives of Physiology & 1996 Tirgoviste C century Biochemistry MEDLINE Database

Slide 7: Fields in a MEDLINE Record

Slide 8: Ovid MEDLINE NLM’s PubMed

Slide 9: Journals Included in MEDLINE  List of journals is easy to find and refer to.  Information about coverage is clearly stated.

Slide 11: MeSH (Medical Subject Headings)  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)

Slide 13: Fields in a MEDLINE Record

Slide 14: Different Terms, Same MeSH Title #1 Title #2 Treatment of Technical considerations gastric cancer. in laparoscopic resection of gastric neoplasms. MeSH headings for both titles: Stomach Neoplasms

Slide 15: Same Term, Different MeSH Title #1 Title #2 The diagnosis of Mechanism of senile plaque-induced plaque formation in periodontal Alzheimer disease. diseases. MeSH heading: MeSH heading: Dental Plaque Senile Plaques

Slide 16: 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

Slide 18: 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.

Slide 19: 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

Slide 21: 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]

Slide 24: From GS Help Anatomy of a Google Scholar Record

Slide 25: GS does it, MEDLINE doesn’t:  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.

Slide 26: 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.

Slide 27: Scope of Google Scholar?????  MEDLINE: >16 million articles back to 1940s  GS: #??? articles back to 19##???

Slide 28: 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?  Ifnot, can you think of all the different text strings that might elicit retrieval?  (And if not, how do you know what you’re missing?)

Slide 29: 2008 2007

Slide 30: 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 vocabulary resource is Answers.com  MeSH developed by NLM  Stedman’s Medical Dictionary originally a main source

Slide 31: 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

Slide 32: 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

Slide 33: Product Feature Comparison MEDLINE Google (via Web of Scholar PubMed) Science Scopus Concept searching?    some Sources list (which     journals, etc.)? Cited reference list?     Citing reference list?     Export to EndNote,  manual   RefWorks? import Score 40% 50% 60% 90%

Slide 34: 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.

Slide 35: Pat Weiss Phone 412.648.2040 pwf@pitt.edu Falk Library Reference Desk Phone 412.648.8796 medlibq@pitt.edu