This paper presents an investigation into the utility of document summarisation in the context of information retrieval, more specifically in the application of so called query biased (or user directed) summaries: summaries customised to reflect the information need expressed in a query. Employed in the retrieved document list displayed after a retrieval took place, the summaries' utility was evaluated in a task-based environment by measuring users' speed and accuracy in identifying relevant documents. This was compared to the performance achieved when users were presented with the more typical output of an IR system: a static predefined summary composed of the title and first few sentences of retrieved documents. The results from the evaluation indicate that the use of query biased summaries significantly improves both the accuracy and speed of user relevance judgements.

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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. IntroductionInformation retrieval (IR) systems aim to provide users with information that will help them in relation to the information need that they expressed to the system (typically in the form of a query). Searchers are then usually involved in the process of evaluating the utility (or the relevance) of the information (i.e., documents) that the IR system retrieves. One of the most common information-seeking situations entails the use of an Internet search engine (Jansen, Spink, & Saracevic, 2000). The availability of information on the World Wide Web (WWW) has established search engines as a major tool for IR and Web documents as a popular medium through which users access information.Assessing the utility of information in relation to an information need is a common task for online searchers. Studies on peoples' perceptions of the relevance of information demonstrate that a range of factors affect human judgements of relevance (e.g., Barry, 1994Barry, , 1998Cool, Belkin, & Kantor, 1993;Maglaughlin & Sonnenwald, 2002;Schamber, 1991). However, such studies often only consider formal textual documents such as journal and conference articles rather than the wide range of formally and informally produced multimedia documents found on the Web. The nature of the IR task on the WWW is different from that on more traditional IR systems (Jansen et al., 2000). One of the differences is the idiosyncrasy of the Web documents themselves. There is generally a large degree of variability in the quality, authority, and layout of Web pages. Moreover, the type of elements such pages contain (e.g., text, multimedia, links) can also vary to a large degree (Woodruff, Aoki, Brewer, Gauthier, & Rowe, 1996), creating a heterogeneous collection of documents distributed over distinct geographic areas.The motivation behind this study was to gain a better understanding of what features make a Web document useful for information seeking. We concentrated specifically on information-seeking tasks-finding Web pages that contain relevant or useful information-because this is one of the prominent uses of Web pages. It is also a task for which there exist ma...

Understanding search behavior is important and leads to more effective interfaces that support searchers throughout the search process. In this article, through an observational user study, we investigate the search behavior of 15 visually impaired and 15 sighted searchers while they complete complex search tasks online. We study complex search tasks because they are challenging, cognitively intensive and affect performance of searchers. We compare the behavior of the two groups of searchers at four stages of the information-seeking process namely, Query Formulation, Search Results Exploration, Query Reformulation, and Search Results Management. For each stage, we identify research questions to investigate the impact of speech-based screen readers on the information-seeking behavior of visually impaired users. Significant differences were observed during query formulation and in the use of query-level support features such as query suggestions and spelling suggestions. In addition, screen-reader users submitted a lower number of queries and displayed comparatively limited exploratory behavior during search results exploration. We investigate how a lack of visual cues affected visually impaired searchers' approach towards query reformulation and observed different strategies to manage and use information encountered during the search process. We discuss the implications that our findings have for the design of search interfaces and propose a set of design guidelines to consider when designing interfaces that are usable and accessible with screen readers. This work also enhances our understanding of search behavior when using an auditory interface and could be useful when designing audio-based information retrieval systems.

Abstract. 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 which 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 towards pairs of documents that jointly possess attributes that are expressed in a query. We experimentally tested three query-sensitive measures against conventional ones that do not take the context of 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 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.