The Web has changed the way in which many researchers access scientific information, conduct research, communicate their findings, and share data. There is now a need to assess the impact of Web publication in order to promote wider and better use of this new medium.1 Recent attempts have been made to go beyond the strict use of bibliometric indicators. Shanghai Jiao Tong University has published a ranking2 of the top 500 universities, in which numbers of publications and citations were combined with other criteria such as institution size or the number of Nobel prizes awarded to alumni.
The Web offers advantages as institutions represent "natural units," with their own institutional domains that mark their presence on the Internet. Since most institutions have a specific Internet domain or subdomain for all their Web pages,3 quantitative data can be extracted using specifically designed crawlers, or the robots of the major search engines.
The contents of these institutional Web sites might include not only final papers or preprints, but also valuable information on other aspects of their scientific activities. Raw data, teaching materials, slides produced for meetings or conferences, in-house software, graphs, media files, and even administrative information might be useful to pupils, colleagues, and partners worldwide. Since the Web is ubiquitous, a wider audience is possible when publication is electronic; this could include readers in developing countries whose access to scientific publications can be very restricted. The Web is cheaper than the printed word and can provide information that paper sources could never contain; for example, large amounts of data, complex and dynamic graphics, or even interactive systems. Finally, the Web is a hypertext-interlinked system, and although the motivations for linking far exceed traditional "citation for recognition," careful use of citation analysis techniques may still be possible.
Web indicators are now becoming important in the quantitative analysis of science,4 but a global system involving the major universities and research institutions has yet to be developed. To fill this gap, we designed a combined assessment model for ranking the institutional domains of universities worldwide based on "Web presence" indicators. Three different features of these domains were assessed: the size of their Web presence (measured by the number of Web pages), visibility (reflected by the number of in-links from pages external to the domain), and the number of "rich" files available (the number of downloadable files in advanced formats such as Adobe Acrobat – pdf, PostScript – ps, MS Word – doc, MS PowerPoint – ppt, and MS Excel – xls).
While evaluations were made in absolute terms, the fact that research and other activities involve specific file types was taken into account. The number of in-links to these organizations' Web sites was used to establish the visibility of their content to third parties, including other academic and scientific organizations, government authorities, and companies.
Data were collected using the major search engines. The full results are available from "Ranking of World Universities in the Web"
A significant positive correlation was found between the Web list ranks and the Shanghai Jiao Tong University list. Moreover, a large number of technologically oriented institutions were well-positioned by the Webometric indicators. The universities of developing countries (especially of the larger nations) appeared in competitive positions with regard to those of the developed world (Table 2).
There are still several technical and methodological problems to overcome, mostly related with the search engine bias. More relevant, there are several shortcomings and caveats related to the use of Web indicators for assessing visibility and impact. These are not yet developed enough to compare directly to bibliometric ones, but we intend to use non-Webometric indicators in our rankings to allow a direct comparison of the different approaches.
Isidro F. Aguillo