In the 18 months since I last taught a class about Google Scholar vs. PubMed, Google has become an even more pervasive presence on the Web. Revisiting Scholar in a Google world, how does it stack up against PubMed−no slouch itself thanks to continuing innovations and improvements?
To a searcher accustomed to PubMed’s Lexus engine, Scholar still rides like a go-kart. Search results are delivered in round numbers (“about 127,000”). You can’t limit search results just to articles, so you may puzzle over the kind of item you are looking at (conference paper? book?). With no controlled vocabulary, a searcher must anticipate all the different terms an author might use to articulate a particular concept. And there is no search history, making it harder to repeat and document searches.
The absence of standardized journal names causes inconsistencies. Search PubMed for either Nature Genetics or Nat Genet as journal title, and you retrieve 5,336 articles. In Scholar, Nat Genet as publication title retrieves about 5,630 items—but Nature Genetics retrieves about 10,400.
But Scholar’s biggest drawback is its vague denominator. Only Google knows its total number of records and names and included dates of covered journals. You can limit results to a subject area, but there is no information on how these are defined.
By contrast, PubMed’s scope is clearly documented: 17,764,826 records (2009 baseline) from 5,398 journals back to 1949. From its link to the National Center for Biotechnology Information (NCBI) Journals database, it is easy to determine whether and how far back a journal is covered and its standardized title. Records have a consistent structure (title, author, source, abstract, etc.) and can be fully displayed. With controlled vocabulary MeSH (Medical Subject Headings), you can search concepts, not just keywords. Search for the MeSH concept stomach neoplasms and get articles whose authors use the terms gastric cancer and gastric neoplasms.
Other PubMed tools include Clinical Queries and Single Citation Matcher. The NCBI environment provides links to molecular biology and genetics databases and to NIH’s free PubMed Central repository. Access PubMed through the “Quick Link” on the HSLS home page, and you’ll automatically get full-text links specific to the University of Pittsburgh.
So what does Scholar offer that PubMed does not? It isn’t the only product with multidisciplinary coverage (try Web of Science or Scopus). Besides journal articles, Scholar has book, scholarly Web site, and conference proceeding records, but this is not unique either.
Scholar’s biggest plus is that it makes full-text articles completely searchable, letting you dig up details like place or personal names that might not surface in a PubMed search. PubMed records may include a link to full text that your institution subscribes to, but never the full text itself. Other Scholar pluses:
- Relevance-ranked search results: in PubMed, ranking is by date;
- Citation data: click on a Cited by link to see citing publications;
- Scholar’s Bibliography Manager: exports records to EndNote and RefWorks automatically—a manual procedure in PubMed.
The conclusion? Both Scholar and PubMed belong in your search tool box. Scholar is ill-defined, but has useful features and retrieves items not in PubMed. For best results, choose precise search terms and configure Advanced Scholar Search to look for them in article titles. For access to all the full text you’re entitled to, configure Scholar Preferences/Library Links by entering University of Pittsburgh.
- Badke W. Google Scholar and the researcher. ONLINE. 33, no. 2(May-Jun 2009):47-9.
- Falagas ME, Pitsouni EI, Malietzis GA, Pappas G. Comparison of PubMed, Scopus, Web of Science, and Google Scholar: strengths and weaknesses. FASEB Journal. 22, no. 2(Feb 2008):338-42.
~ Patricia Weiss