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As a student, I enjoy the extreme privilege of being able to access almost any information resources I need for research purposes, thanks to the extensive university library network. But for those of us in the commercial search world, things aren’t so easy. Comparing major search products is essential when search resources are limited (which is always!). Last time in this series we examined the number of titles in Web of Science vs. Scopus, and the overlap between the two. In this post we’ll discover some other points of comparison in their collection scope and coverage.
In my last post, the angle used to compare the two databases was the number of individual titles (e.g. journals) covered. Covering an impressively large number of academic journals can make a database seem very appealing. However, this appeal is tempered when you realize that search engines such as Google Scholar are indexing massive numbers of journals as well, as publishers make their article titles and abstracts more “visible” to Google. Note that Elsevier, the producer of Scopus, also allows Google Scholar to index Elsevier publications through their free search portal, ScienceDirect. The larger and more diverse a database is, the more the “noise,” or percentage of irrelevant hits, increases. Think of the quality of results found in a specially targeted search file, such as Inspec, when compared with a general web search on the same keywords. Google Scholar’s massive and diverse coverage base can sometimes make their search results noisy and full of false hits, prompting us to remember that high search accuracy is sometimes desirable over massive search recall.
We’ve already determined there’s a pretty large percentage overlap between Scopus and Web of Science, but what about the unique contents of these files? One way to contrast the two files is to look at their content broken down by record type. We know that scientific and technical information can be found in journals, conference proceedings, reports, white papers, and any number of gray literature documents. According to the data provided to the JISC-ADAT website, the Scopus database is made up of the following publication types:
Scholarly Journal 93.12%, Trade Journal 2.62%, Report 2.44%, Book In Series 1.82%
While Web of Science lists the following breakdown:
Scholarly Journal 98.18%, Book In Series 1.82%
If the JISC-ADAT reporting is reliable, it seems that Scopus may have a wider array of trade journals and reports than Web of Science can offer, although both files are made up of primarily journal articles.
Comparing the global profiles of the two files is another way to evaluate their differences. High quality scientific and technical literature is generated all over the world, and the “country of publication” pie charts for these databases are beginning to diversify. The geographic makeup of these two files will be of particular interest for prior art searchers, as their searches frequently are required to be international.
Here is the JISC-ADAT entry for geographic coverage for Scopus:
We can see that there is strong coverage for Asia, and emerging emphasis in South America.
Here is the same JISC-ADAT graph for Web of Science:
Web of Science looks like it puts slightly less emphasis on Asia when compared with Scopus, specifically when comparing coverage for China and Indonesia. It may also have comparatively lighter coverage for some South American countries.
Below are country of publication breakdowns by percentage for both Scopus and Web of Science:
Based on these numbers, which were last updated for both systems in November 2010, it seems that Scopus may offer a wider range of titles not published in the US, and that it may especially offer an advantage when it comes to China. Thomson Reuters does offer a separate product, called the Chinese Science Citation database, which offers coverage for about 1,200 scholarly publications from China, but this seems to be a separate product which has not been merged into the Web of Science collection.
In my next post I’ll take a look at some more features that distinguish these products. In the meantime, what are your thoughts on the strengths and weaknesses of these two sci/tech search giants?
This post was contributed by Landon IP Librarian Kristin Whitman. The Intellogist blog is provided for free by Intellogist’s parent company, Landon IP, a major provider of patent search, technical translation, and information services.