Anastasios Tombros

How users assess web pages for information seeking

In this article, we investigate the criteria used by online searchers when assessing the relevance of Web pages for information-seeking tasks. Twenty-four participants were given three tasks each, and they indicated the features of Web pages that they used when deciding about the usefulness of the pages in relation to the tasks. These tasks were presented within the context of a simulated work-task situation. We investigated the relative utility of features identified by participants (Web page content, structure, and quality) and how the importance of these features is affected by the type of information-seeking task performed and the stage of the search. The results of this study provide a set of criteria used by searchers to decide about the utility of Web pages for different types of tasks. Such criteria can have implications for the design of systems that use or recommend Web pages.

The effectiveness of query-specific hierarchic clustering in information retrieval

Hierarchic document clustering has been widely applied to information retrieval (IR) on the grounds of its potential improved effectiveness over inverted file search (IFS). However, previous research has been inconclusive as to whether clustering does bring improvements. In this paper we take the view that if hierarchic clustering is applied to search results (query-specific clustering), then it has the potential to increase the retrieval effectiveness compared both to that of static clustering and of conventional IFS. We conducted a number of experiments using five document collections and four hierarchic clustering methods. Our results show that the effectiveness of query-specific clustering is indeed higher, and suggest that there is scope for its application to IR.

Query-sensitive similarity measures for information retrieval

The application of document clustering to information retrieval has been motivated by the potential effectiveness gains postulated by the cluster hypothesis. The hypothesis states that relevant documents tend to be highly similar to each other and therefore tend to appear in the same clusters. In this paper we propose an axiomatic view of the hypothesis by suggesting that documents relevant to the same query (co-relevant documents) display an inherent similarity to each other that is dictated by the query itself. Because of this inherent similarity, the cluster hypothesis should be valid for any document collection. Our research describes an attempt to devise means by which this similarity can be detected. We propose the use of query-sensitive similarity measures that bias interdocument relationships toward pairs of documents that jointly possess attributes expressed in a query. We experimentally tested three query-sensitive measures against conventional ones that do not take the query into account, and we also examined the comparative effectiveness of the three query-sensitive measures. We calculated interdocument relationships for varying numbers of top-ranked documents for six document collections. Our results show a consistent and significant increase in the number of relevant documents that become nearest neighbors of any given relevant document when query-sensitive measures are used. These results suggest that the effectiveness of a cluster-based information retrieval system has the potential to increase through the use of query-sensitive similarity measures.

Report on the INEX 2004 interactive track

As scientific data repositories, digital libraries and publishers increasingly use the eXtensible Markup Language (XML) for publication and storage interest has arisen in exploiting this formatting for retrieval purposes. XML is attractive because it defines the logical structure of the documents and has the potential to assist IR systems in providing more appropriate results to users, i.e., to return relevant document components (i.e. XML elements) rather than whole documents. In addition, the XML tags often have specific semantics that may be exploited purposefully in IR.

Evaluating XML retrieval effectiveness at INEX

The INitiative for the Evaluation of XML retrieval (INEX) was set up in 2002 to establish an infrastructure and provide means, in the form of large test collections and appropriate scoring methods, for evaluating the effectiveness of content-oriented XML retrieval systems. This report provides an overview of the evaluation methodology developed in INEX from 2002 to 2006.

Designing a user interface for interactive retrieval of structured documents — lessons learned from the INEX interactive track

The interactive track of the Initiative for the Evaluation of XML retrieval (INEX) aims at collecting empirical data about user interaction behaviour and to build methods and algorithms for supporting interactive retrieval in digital library systems containing structured documents. In this paper we discuss and compare the usability aspects of the web-based user interface used in 2004 with the application based user interface implemented with the Daffodil framework in 2005. The results include a validation of the element retrieval approach, successful implementation of the berrypicking model, and that additional clues for facilitating interactive retrieval (e.g. table of contents, indication of entry points, related terms, etc.) are appreciated by users.

Factors affecting web page similarity

Tools that allow effective information organisation, access and navigation are becoming increasingly important on the Web. Similarity between web pages is a concept that is central to such tools. In this paper, we examine the effect that content and layout-related aspects of web pages have on web page similarity. We consider the textual content contained within common HTML tags, the structural layout of pages, and the query terms contained within pages. Our study shows that combinations of factors can yield more promising results than individual factors, and that different aspects of web pages affect similarities between pages in a different manner. We found a number of factors that, when taken into account, can result in effective measures of similarity between web pages. Query information in particular, proved to be important for the effective organisation of web pages.

Query-sensitive similarity measures for the calculation of interdocument relationships

The application of document clustering to information retrieval has been motivated by the potential effectiveness gains postulated by the Cluster Hypothesis. The hypothesis states that relevant documents tend to be highly similar to each other, and therefore tend to appear in the same clusters. In this paper we propose that, for any given query, pairs of relevant documents will exhibit an inherent similarity which is dictated by the query itself. Our research describes an attempt to devise means by which this similarity can be detected. We propose the use of query-sensitive similarity measures that bias interdocument relationships towards pairs of documents that jointly possess attributes that are expressed in a query. We experimentally tested query-sensitive measures against conventional ones that do not take the context of the query into account. We calculated interdocument relationships for varying numbers of top-ranked documents for five document collections. Our results show a consistent and significant increase in the number of relevant documents that become nearest neighbours of any given relevant document when query-sensitive measures are used. These results suggest that the effectiveness of a cluster-based IR system has the potential to increase through the use of query-sensitive similarity measures.

Is XML retrieval meaningful to users?: searcher preferences for full documents vs. elements

The aim of this study is to investigate whether element retrieval (as opposed to full-text retrieval) is meaningful and useful for searchers when carrying out information-seeking tasks. Our results suggest that searchers find the structural breakdown of documents useful when browsing within retrieved documents, and provide support for the usefulness of element retrieval in interactive settings.

INEX 2002-2006: understanding XML retrieval evaluation

Evaluating the effectiveness of XML retrieval requires building test collections where the evaluation paradigms are provided according to criteria that take into account structural aspects. The INitiative for the Evaluation of XML retrieval (INEX) was set up in 2002, and aimed to establish an infrastructure and to provide means, in the form of large test collections and appropriate scoring methods, for evaluating the effectiveness of content-oriented XML retrieval. This paper describes the evaluation methodology developed in INEX, with particular focus on how evaluation metrics and the notion of relevance are treated.