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While technological advances have enabled us to access extensive document collections, formulating a query which is well designed for an information retrieval (IR) system remains a difficult task. A number of methods have been developed to support user query formulation and reformulation based on terminological feedback. Terminological feedback offers a set of terms that can be used to modify an existing query. This also gives users an opportunity to transform a part of the query reiformulation process to term selection: a potentially simpler task. There is, however, much room for investigating and improving the interaction between users and IR systems with regard to query reiformulation. The limited context and structure of suggested terms are just some of the problems found with existing methods. This thesis presents a new approach to supporting user query reformulation and searching. The approach is based on hierarchical organisation of terms, which is dynamically derived from a set of retrieved documents. This thesis investigates both statistical and lexical aspects of terms as a means of deriving a hierarchy from texts. As a summative evaluation of our approach, a user study is carried out to investigate several aspects of the user interaction with our support system. A search interface is developed to integrate a visualised hierarchy into a search result of an IR system. Two types of hierarchies are evaluated based on a TREe test collection, and compared to a baseline that has no hierarchy. Results suggest that multiple aspects of information searching process can be supported by the hierarchies. In particular, the range of search vocabulary employed to complete a task is shown to increase, and browsing of retrieved documents is found to be facilitated by the hierarchies. |
