by John Borghi
If you are a researcher who commonly uses Google Scholar or Web of Science to collect and discover reference material, you may have noticed some recent additions to the two services. As a result of a recent partnership between Google and Thompson Reuters, Google Scholar and Web of Science now provide reciprocal linking. The results of searches made using Google Scholar now include citation information and full text links offered through Web of Science’s core collection and article records in Web of Science now include links to search for the full text on Google Scholar. Provided you are working at an institution with a Web of Science subscription, moving between the two services is now a matter of just a few mouse clicks. However, despite this integration, the two services have distinct strengths and weaknesses. For this reason, an effective literature search generally requires the use of not just Google Scholar and Web of Science, but possibly also other citation indices including Scopus.
Google Scholar and the Open Web
Owing to the strength of its search algorithms and simple user interface, Google Scholar is increasingly the starting point for researchers looking for reference material. For most users, especially those with institutional access to services like Web of Science and Scopus, accessing the full text of a reference is often just a matter of googling its title and clicking through the Google Scholar link. Because it often includes links to material hosted in institutional repositories and on author websites, Google Scholar is often the best tool for locating the full text of a particular journal article or book chapter. Unfortunately, Google Scholar’s strength in returning the full text of references belies its relative weakness in identifying relevant references when bibliographical information (title, authors, etc) is unknown or when searches are relatively general.
Perhaps the biggest weakness of Google Scholar is the secrecy surrounding the breadth and frequency of its updates. Lists of academic publications currently indexed by Google Scholar and update schedules for currently indexed publications are not publicly available. Though most major publishers have now agreed to allow Google to index their databases, this has not always been the case and there is little guarantee that this will continue in the future. For example, prior to 2008, Elsevier, publisher of Cell, the Current Opinions and Trends series of journals and many other prestigious publications did not allow Google to index its databases. As of this writing, recent publications by the American Chemical Society (including the prestigious Journal of the American Chemical Society) are still not available.
Though Google’s ranking algorithm is not publicly known, citation counts appear to play a large role. Because Google Scholar indexes patents, theses, and conference posters alongside articles and book chapters, its citation counts are often significantly inflated compared to other services. In practice, this causes seminal papers to be returned first, with less cited papers often ranked alongside non-academic material. Combined with the fact that Google Scholar presently does not distinguish between peer reviewed and non-reviewed material and its tendency to return different versions of the same paper as if they were wholly separate references, and it can quickly become quite difficult (not to mention tedious) to find relevant references with low citation counts. Thus, as useful as Google Scholar may be for locating full text versions of particular references, it is generally easier and more efficient to use other services when conducting searches by subject area or by keyword.
Web of Science and other Subscription-Based Services
The major strength of subscription-based services such as Web of Science is their curation. Thomson Reuters maintains a searchable master list of the journals indexed in Web of Science and updates are weekly- with new articles appearing approximately two weeks after appearing in print. Because subscription-based services generally maintain a tighter degree of control over bibliographical information and version histories than Google Scholar, they are often the best choice when searching for references by author name, subject area, or keyword. Also, because
Thompson Reuters publishes bibliographic indicators such as impact factor (IF) for the journals indexed in Web of Science, researchers are able to evaluate the prestige and influence of reference material- though they should do so carefully. The major weakness of Web of Science and other subscription based services is their coverage. Web of Science currently indexes tens of thousands of peer reviewed journals. However, articles published online ahead of print are not included- meaning that there may be significant gaps between when an article is made available via a journal and when that article may appear in a reference search. Scopus does index “online early” articles but, especially for journals from small publishers, papers that have since been published in print often incorrectly remain listed as being “in press.”
Finding the Articles You Need
Just as Google Scholar’s links to articles hosted in institutional repositories and on author websites makes it ideal for finding the full text of particular references, the curation articles by subscription-based services such as Web of Science make them ideal for performing relatively general references searches. Thus, before thinking about which service to use, think about the type of search you want to conduct. Using Google Scholar to perform a relatively general search may seem like a reasonable idea (it is a Google product after all) until you spend an afternoon wading through page after page articles from unreliable journals, patents, and theses. At the same time, you may have little to no luck if you try to locate the full text of a recent paper using a subscription-based service.
To do an exhaustive search on a particular topic, my advice would be to use multiple services. Use a subscription-based service such as Web of Science to search by subject area or keyword- or, for maximum coverage- use multiple services and then use Google to track down the full texts of specific references. With the new links between Web of Science and Google Scholar, this is easier than ever… provided you are are working with a university subscription.
Falagas, M. E., Pitsouni, E. I., Malietzis, G. A., & Pappas, G. (2008). Comparison of PubMed, Scopus, Web of Science, and Google scholar: strengths and weaknesses. The FASEB Journal, 22(2), 338-342.