• A comparison of sources of links for academic Web impact factor calculations

      Thelwall, Mike (MCB UP Ltd, 2002)
      There has been much recent interest in extracting information from collections of Web links. One tool that has been used is Ingwersen¿s Web impact factor. It has been demonstrated that several versions of this metric can produce results that correlate with research ratings of British universities showing that, despite being a measure of a purely Internet phenomenon, the results are susceptible to a wider interpretation. This paper addresses the question of which is the best possible domain to count backlinks from, if research is the focus of interest. WIFs for British universities calculated from several different source domains are compared, primarily the .edu, .ac.uk and .uk domains, and the entire Web. The results show that all four areas produce WIFs that correlate strongly with research ratings, but that none produce incontestably superior figures. It was also found that the WIF was less able to differentiate in more homogeneous subsets of universities, although positive results are still possible.
    • A layered approach for investigating the topological structure of communities in the Web.

      Thelwall, Mike (MCB UP Ltd, 2003)
      A layered approach for identifying communities in the Web is presented and explored by applying the flake exact community identification algorithm to the UK academic Web. Although community or topic identification is a common task in information retrieval, a new perspective is developed by: the application of alternative document models, shifting the focus from individual pages to aggregated collections based upon Web directories, domains and entire sites; the removal of internal site links; and the adaptation of a new fast algorithm to allow fully-automated community identification using all possible single starting points. The overall topology of the graphs in the three least-aggregated layers was first investigated and found to include a large number of isolated points but, surprisingly, with most of the remainder being in one huge connected component, exact proportions varying by layer. The community identification process then found that the number of communities far exceeded the number of topological components, indicating that community identification is a potentially useful technique, even with random starting points. Both the number and size of communities identified was dependent on the parameter of the algorithm, with very different results being obtained in each case. In conclusion, the UK academic Web is embedded with layers of non-trivial communities and, if it is not unique in this, then there is the promise of improved results for information retrieval algorithms that can exploit this additional structure, and the application of the technique directly to partially automate Web metrics tasks such as that of finding all pages related to a given subject hosted by a single country's universities.
    • Can Google's PageRank be used to find the most important academic Web pages?

      Thelwall, Mike (MCB UP Ltd, 2003)
      Google's PageRank is an influential algorithm that uses a model of Web use that is dominated by its link structure in order to rank pages by their estimated value to the Web community. This paper reports on the outcome of applying the algorithm to the Web sites of three national university systems in order to test whether it is capable of identifying the most important Web pages. The results are also compared with simple inlink counts. It was discovered that the highest inlinked pages do not always have the highest PageRank, indicating that the two metrics are genuinely different, even for the top pages. More significantly, however, internal links dominated external links for the high ranks in either method and superficial reasons accounted for high scores in both cases. It is concluded that PageRank is not useful for identifying the top pages in a site and that it must be combined with a powerful text matching techniques in order to get the quality of information retrieval results provided by Google.
    • Commercial Web site links.

      Thelwall, Mike (MCB UP Ltd, 2001)
      Every hyperlink pointing at a Web site is a potential source of new visitors, especially one near the top of a results page from a popular search engine. The order of the links in a search results page is often decided upon by an algorithm that takes into account the number and quality of links to all matching pages. The number of standard links targeted at a site is therefore doubly important, yet little research has touched on the actual interlinkage between business Web sites, which numerically dominate the Web. Discusses business use of the Web and related search engine design issues as well as research on general and academic links before reporting on a survey of the links published by a relatively random collection of business Web sites. The results indicate that around 66 percent of Web sites do carry external links, most of which are targeted at a specific purpose, but that about 17 percent publish general links, with implications for those designing and marketing Web sites.
    • Finding similar academic Web sites with links, bibliometric couplings and colinks

      Thelwall, Mike; Wilkinson, David (Elsevier, 2004)
      A common task in both Webmetrics and Web information retrieval is to identify a set of Web pages or sites that are similar in content. In this paper we assess the extent to which links, colinks and couplings can be used to identify similar Web sites. As an experiment, a random sample of 500 pairs of domains from the UK academic Web were taken and human assessments of site similarity, based upon content type, were compared against ratings for the three concepts. The results show that using a combination of all three gives the highest probability of identifying similar sites, but surprisingly this was only a marginal improvement over using links alone. Another unexpected result was that high values for either colink counts or couplings were associated with only a small increased likelihood of similarity. The principal advantage of using couplings and colinks was found to be greater coverage in terms of a much larger number of pairs of sites being connected by these measures, instead of increased probability of similarity. In information retrieval terminology, this is improved recall rather than improved precision.
    • MuTaTeD’ll A System for Music Information Retrieval of Encoded Music

      Boehm, Carola (Library and Information Commission, 2001)
      This is the final publication of the results of the project “MuTaTed’II”, A system for Information Retrieval of Encoded Music”. The aim of the project was to design and implement an information retrieval system with delivery/access services for digital music and sound. The project was documented and the results presented at various conferences; (ICMC 2000 Berlin, ISMI 2000 Massachusetts, Euromicro 2000 Amsterdam).
    • New versions of PageRank employing alternative Web document models

      Thelwall, Mike; Vaughan, Liwen (Emerald Group Publishing Limited, 2004)
      Introduces several new versions of PageRank (the link based Web page ranking algorithm), based on an information science perspective on the concept of the Web document. Although the Web page is the typical indivisible unit of information in search engine results and most Web information retrieval algorithms, other research has suggested that aggregating pages based on directories and domains gives promising alternatives, particularly when Web links are the object of study. The new algorithms introduced based on these alternatives were used to rank four sets of Web pages. The ranking results were compared with human subjects’ rankings. The results of the tests were somewhat inconclusive: the new approach worked well for the set that includes pages from different Web sites; however, it does not work well in ranking pages that are from the same site. It seems that the new algorithms may be effective for some tasks but not for others, especially when only low numbers of links are involved or the pages to be ranked are from the same site or directory.
    • Research note: in praise of Google: finding law journal Web sites

      Thelwall, Mike (MCB UP Ltd, 2002)
      Google is a highly regarded and widely used search engine, particularly in academia. In this short note we comment on its remarkable ability to find journal Web sites, using a case study of law.
    • Subject gateway sites and search engine ranking.

      Thelwall, Mike (MCB UP Ltd, 2002)
      The spread of subject gateway sites can have an impact on the other major Web information retrieval tool: the commercial search engine. This is because gateway sites perturb the link structure of the Web, something used to rank matches in search engine results pages. The success of Google means that its PageRank algorithm for ranking the importance of Web pages is an object of particular interest, and it is one of the few published ranking algorithms. Although highly mathematical, PageRank admits a simple underlying explanation that allows an analysis of its impact on Web spaces. It is shown that under certain stated assumptions gateway sites can actually decrease the PageRank of their targets. Suggestions are made for gateway site designers and other Web authors to minimise this.