Despite citation counts from Google Scholar (GS), Web of Science (WoS), and Scopus being widely consulted by researchers and sometimes used in research evaluations, there is no recent or systematic evidence about the differences between them. The results from attached work suggest that in all areas GS citation data is essentially a superset of WoS and Scopus, with substantial extra coverage.
Google Scholar has of course more coverage because almost any website identified as a scientific journal is indexed there. This includes even predatory journals, even if you uploaded a poster on RG with citations, it will appear there. Also, theses on university websites appear there. Being inclusive is good (more coverage / higher sensitivity) and bad in the same time (predatory publishers use this indexing to convince authors they are real). Therefore, most universities use SCOPUS or Web of Science for assessment of research output.
Google scholar citation is a better evaluator, since only journals indexed on Google scholar are picked up.
Hi,
GS is a search engine, and WoS and Scopus are subscription databases. There is a difference between the indexing in an open search engine, that is inclusive but not selective, and the indexing of databases that have criteria for inclusion in the database. There is a lot of material in GS, but this does not indicate quality, since much of what is included cannot be classified according to type of material, country of origin, research area etc', all those indicators that you can find in a database.
Google Scholar has of course more coverage because almost any website identified as a scientific journal is indexed there. This includes even predatory journals, even if you uploaded a poster on RG with citations, it will appear there. Also, theses on university websites appear there. Being inclusive is good (more coverage / higher sensitivity) and bad in the same time (predatory publishers use this indexing to convince authors they are real). Therefore, most universities use SCOPUS or Web of Science for assessment of research output.
Many relevant comments. Thanks.
Google scholar can not be compared to scopus and wok as GS is basically dedicated to report all available publications where ever they come from without any consideration of quality per se.
This does not mean that its content is not relevant. On the contrary of Scopus and WOK, GS does not choose among publications before indexing them. Eventually these are the readers that give the publications their interest by citing them. Publications of less interest will not be cited. Thus the quality will come from the everyone's assessment of works and not only from a small group of people leading the private editions who actually rule our work, as our administrations just use these private groups indexes to assess our work.
Dear Omer Tontus,
Browsing the paper you cited, I think that the authors of the paper well analyzed the citations of the three systems and that their result is reliable. So, I agree that in all areas Google Scholar citation data is essentially a superset of Web of Science and Scopus, with substantial extra coverage.
Best regards,
Tatsuo Tabata
I think it’s true.
Roughly speaking it comes down to the following:
The Web of Science citations are considered to be the most reliable (debatable, but that’s the consensus in the academic world). Only journals and subsequent citations are counted that meet certain criteria are included in their database.
Scopus is rather complete because it also includes chapters of books. Again only journals and subsequent citations that meet certain criteria are included in their database.
Google scholar includes almost all of the above citations and in addition also includes:
-Journals not indexed in one of the above database
-References of (PhD)thesis all around the world (provided that a full-text copy is downloadable)
-Conference papers (and sometimes even posters)
-All other types of scholar production (instruction manuals for educational purposes for example, presentations, etc.)
-Last but not least patents
In other words Google scholar is given the best impression of the scientific impact of a publication. Although some scholarly work is considered less valuable (not peer reviewed, not published in (high) impact journal etc.) to me it is informative to see that a particular paper receives attention besides the ‘regular’ citations.
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