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Vaughan, L.; Thelwall, M.: Search engine coverage bias : evidence and possible causes (2004)
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- Abstract
- Commercial search engines are now playing an increasingly important role in Web information dissemination and access. Of particular interest to business and national governments is whether the big engines have coverage biased towards the US or other countries. In our study we tested for national biases in three major search engines and found significant differences in their coverage of commercial Web sites. The US sites were much better covered than the others in the study: sites from China, Taiwan and Singapore. We then examined the possible technical causes of the differences and found that the language of a site does not affect its coverage by search engines. However, the visibility of a site, measured by the number of links to it, affects its chance to be covered by search engines. We conclude that the coverage bias does exist but this is due not to deliberate choices of the search engines but occurs as a natural result of cumulative advantage effects of US sites on the Web. Nevertheless, the bias remains a cause for international concern.
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Thelwall, M.: Web impact factors and search engine coverage (2000)
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- Abstract
- Search engines index only a proportion of the web and this proportion is not determined randomly but by following algorithms that take into account the properties that impact factors measure. A survey was conducted in order to test the coverage of search engines and to decide thether their partial coverage is indeed an obstacle to using them to calculate web impact factors. The results indicate that search engine coverage, even of large national domains is extremely uneven and would be likely to lead to misleading calculations
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Thelwall, M.: Extracting accurate and complete results from search engines : case study windows live (2008)
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- Abstract
- Although designed for general Web searching, Webometrics and related research commercial search engines are also used to produce estimated hit counts or lists of URLs matching a query. Unfortunately, however, they do not return all matching URLs for a search and their hit count estimates are unreliable. In this article, we assess whether it is possible to obtain complete lists of matching URLs from Windows Live, and whether any of its hit count estimates are robust. As part of this, we introduce two new methods to extract extra URLs from search engines: automated query splitting and automated domain and TLD searching. Both methods successfully identify additional matching URLs but the findings suggest that there is no way to get complete lists of matching URLs or accurate hit counts from Windows Live, although some estimating suggestions are provided.
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Thelwall, M.: Quantitative comparisons of search engine results (2008)
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- Abstract
- Search engines are normally used to find information or Web sites, but Webometric investigations use them for quantitative data such as the number of pages matching a query and the international spread of those pages. For this type of application, the accuracy of the hit count estimates and range of URLs in the full results are important. Here, we compare the applications programming interfaces of Google, Yahoo!, and Live Search for 1,587 single word searches. The hit count estimates were broadly consistent but with Yahoo! and Google, reporting 5-6 times more hits than Live Search. Yahoo! tended to return slightly more matching URLs than Google, with Live Search returning significantly fewer. Yahoo!'s result URLs included a significantly wider range of domains and sites than the other two, and there was little consistency between the three engines in the number of different domains. In contrast, the three engines were reasonably consistent in the number of different top-level domains represented in the result URLs, although Yahoo! tended to return the most. In conclusion, quantitative results from the three search engines are mostly consistent but with unexpected types of inconsistency that users should be aware of. Google is recommended for hit count estimates but Yahoo! is recommended for all other Webometric purposes.
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Thelwall, M.: Assessing web search engines : a webometric approach (2011)
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- Abstract
- Information Retrieval (IR) research typically evaluates search systems in terms of the standard precision, recall and F-measures to weight the relative importance of precision and recall (e.g. van Rijsbergen, 1979). All of these assess the extent to which the system returns good matches for a query. In contrast, webometric measures are designed specifically for web search engines and are designed to monitor changes in results over time and various aspects of the internal logic of the way in which search engine select the results to be returned. This chapter introduces a range of webometric measurements and illustrates them with case studies of Google, Bing and Yahoo! This is a very fertile area for simple and complex new investigations into search engine results.
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Thelwall, M.; Binns, R.; Harries, G.; Page-Kennedy, T.; Price, L.; Wilkinson, D.: Custom interfaces for advanced queries in search engines (2001)
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- Abstract
- Those seeking information from the Internet often start from a search engine, using either its organised directory structure or its text query facility. In response to the difficulty in identifying the most relevant pages for some information needs, many search engines offer Boolean text matching and some, including Google, AltaVista and HotBot, offer the facility to integrate additional information into a more advanced request. Amongst web users, however, it is known that the employment of complex enquiries is far from universal, with very short queries being the norm. It is demonstrated that the gap between the provision of advanced search facilities and their use can be bridged, for specific information needs, by the construction of a simple interface in the form of a website that automatically formulates the necessary requests. It is argued that this kind of resource, perhaps employing additional knowledge domain specific information, is one that could be useful for websites or portals of common interest groups. The approach is illustrated by a website that enables a user to search the individual websites of university level institutions in European Union associated countries.
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Thelwall, M.: Directing students to new information types : a new role for Google in literature searches? (2005)
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- Abstract
- Conducting a literature review is an important activity for postgraduates and many undergraduates. Librarians can play an important role, directing students to digital libraries, compiling online subject reSource lists, and educating about the need to evaluate the quality of online resources. In order to conduct an effective literature search in a new area, however, in some subjects it is necessary to gain basic topic knowledge, including specialist vocabularies. Google's link-based page ranking algorithm makes this search engine an ideal tool for finding specialist topic introductory material, particularly in computer science, and so librarians should be teaching this as part of a strategic literature review approach.
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Thelwall, M.; Vaughan, L.: New versions of PageRank employing alternative Web document models (2004)
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- Abstract
- 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.
