Google Scholar (GS) is a search engine that indexes scholarly literature that is either accessible online (university websites etc.) or for which Google has been given permission to crawl selected publisher databases.
GS offers a broader coverage of publication types and research fields than the traditional citation indexes. For many academics, it is an attractive information retrieval tool that provides quick, free access to data on millions of published documents in all languages from all over the world.
GS is basically built on automatic indexing in the same way as 'ordinary' Google. However, GS is marketed as a service that filters content in such a way that a search only lists 'scholarly literature.'
'Scholarly' normaly refers to literature that has gone through a process of peer review. The automatic indexing would imply that 'scholarly' in a GS context is determined according to where the document is posted (e.g. on 'edu' sites) and on the document's structure (title, author and reference list). GS provides the following advice to authors wishing to make a publication visible via GS:
"If you're an individual author, it works best to simply upload your article to your website, e.g., www.example.edu/~professor/jpdr2009.pdf; and add a link to it on your publications page, such as www.example.edu/~professor/publications.html. Make sure that:
- the full text of your article is in a PDF file that ends with ".pdf",
- the title of the article appears in a large font on top of the first page,
- the authors of the article are listed right below the title on a separate line, and
- there's a bibliography section titled, e.g., "References" or "Bibliography" at the end."
However, it is not clear which publishers GS collaborates with, nor is there any official explanation of the types of documents GS considers to be scholarly (Gray et al., 2012).
GS and citations
If GS is used for citation counts, the scanty documentation of the coverage of the search engine and its underlying data processing has even greater significance. Despite the fact that GS allows citations of non-English-language articles and books to be counted, it is worth noting that studies (such as Jacsó, 2010) indicate the occurrence of fundamental errors in GS data processing, which means that the citation counts can include:
- False hits (where a citation is connected with the wrong publication)
- Double counts (where different versions of the same reference list count as citations of the same publications)
- Missing hits (where a citation is not connected with any publication)
- Citations from non-academic sources (where the automatic filtering of academic literature does not filter out non-academic literature)
If, on the other hand, GS is used qualitatively and to a moderate degree – for instance, to see 'who' is citing a certain academic or a certain publication – the aforementioned errors are not as serious and can even be an effective way of identifying potential collaborative partners.
Search more effectively in GS
Anne-Will Harzing, Professor of International Management and Associate Dean of Research at the University of Melbourne, developed free software that facilitates the analysis of results from searches in GS. The application is called ''Publish or Perish'' and allows you to clean up some of the many data errors in GS, while helping to calculate a number of common citation indicators (average h-index).
Google Scholar Citations is Google's service for citation counts based on GS.
Read more about GS
Google Scholar – About (2012) http://scholar.google.com/intl/en/scholar/about.html
Peter Jacsó (2010). Megadata mega mess in Google Scholar. Online Information Review, vol. 34, Iss. 1, pp. 175-191. http://dx.doi.org/10.1108/14684521011024191
Jerry E. Gray et al. (2012). Scholarish: Google Scholar and its value to the sciences. In: Issues in Science and Technology Librarianship, Iss. 70 (summer 2012). http://www.istl.org/12-summer/article1.html