A New Era in Citation and Bibliometric Analyses: Web of Science, Scopus, and Google Scholar
June 21, 2007 Leave a comment
Lokman I. Meho and Kiduk Yang
School of Library and Information Science, Indiana University, 2007
Academic institutions, federal agencies, publishers, editors, authors, and librarians increasingly rely on citation analysis for making hiring, promotion, tenure, funding, and/or reviewer and journal evaluation and selection decisions. The Institute for Scientific Information’s (ISI) citation databases have been used for decades as a starting point and often as the only tools for locating citations and/or conducting citation analyses. ISI databases (or Web of Science), however, may no longer be adequate as the only or even the main sources of citations because new databases and tools that allow citation searching are now available. Whether these new databases and tools complement or represent alternatives to Web of Science (WoS) is important to explore. Using a group of 15 library and information science faculty members as a case study, this paper examines the effects of using Scopus and Google Scholar (GS) on the citation counts and rankings of scholars as measured by WoS. The paper discusses the strengths and weaknesses of WoS, Scopus, and GS, their overlap and uniqueness, quality and language of the citations, and the implications of the findings for citation analysis. The project involved citation searching for approximately 1,100 scholarly works published by the study group and over 200 works by a test group (an additional 10 faculty members). Overall, more than 10,000 citing and purportedly citing documents were examined. WoS data took about 100 hours of collecting and processing time, Scopus consumed 200 hours, and GS a grueling 3,000 hours.
Conclusions by the authors:
The study found that the addition of Scopus citations to those of WoS could significantly alter the ranking of scholars. The study also found that GS stands out in its coverage of conference proceedings as well as international, non-English language journals, among others. GS also indexes a wide variety of document types, some of which may be of significant value to researchers. The use of Scopus and GS, in addition to WoS, reveals a more comprehensive and accurate picture of the extent of the scholarly relationship between LIS and other fields, as evidenced by the unique titles that cite LIS literature (e.g., titles from Cognitive Science, Computer Science, Education, and Engineering, to name only a few). Significantly, this study has demonstrated that:
- Although WoS remains an indispensable citation database, it should not be used alone for locating citations to an author or title, and, by extension, journals, departments, and countries; Scopus should be used concurrently.
- Although Scopus provides more comprehensive citation coverage of LIS and LIS-related literature than WoS for the period 1996-2005, the two databases complement rather than replace each other.
- While both Scopus and GS help identify a considerable number of citations not found in WoS, only Scopus significantly alters the ranking of scholars as measured by WoS.
Although GS unique citations are not of the same quality as those found in WoS or Scopus, they could be very useful in showing evidence of broader international impact than could possibly be done through the two proprietary databases.
- GS value for citation searching purposes is severely diminished by its inherent problems. GS data are not limited to refereed, high quality journals and conference proceedings. GS is also very cumbersome to use and needs significant improvement in the way it displays search results and the downloading capabilities it offers for it to become a useful tool for large-scale citation analyses.
- Given the low overlap or high uniqueness between the three tools, they may all be necessary to develop more accurate maps or visualizations of scholarly networks and impact both within and between disciplines (Börner, Chen, & Boyack, 2003; Börner, Sanyal, & Vespignani, 2006; Small, 1999; White & McCain, 1997).
- Each database or tool requires specific search strategy(ies) in order to collect citation data, some more accurately and quickly (i.e., WoS and Scopus) than others (i.e., GS).
(Accepted for publication in the Journal of the American Society for Information Science and Technology)