| The goal of this dissertation was to understand whether simulating a human intermediary that has the domain knowledge and its structure would support a user's Web searching tasks. This research applied the mediated access through a collection in a specific domain, and a combined display of a clustered structure and a linear ranked list of search results as the simulated intermediary. We investigated whether the existence of either the mediation condition and/or the display condition would affect the three main measures of the user's Web searching behaviors: effectiveness, efficiency, and usability. The goals of this dissertation were accomplished by conducting an experimental study of Web information-seeking. Subjects were provided with four tasks with limited time given, all requiring some domain knowledge regarding environmental issues. Detailed user behaviors were collected via questionnaires, logged data, and exit interview. The results of the study demonstrated that the mediation condition or the display condition did not have much effect on the three measures. However, all these measures had interesting results via further analyses considering three important factors; the order of the tasks, topic easiness, and system usage order. The mediated system and the combined display were more effective, efficient, or useful than the non-mediated system and the linear ranked list as a user conducted more information searching tasks, when the given topic was easy/difficult, and when the searcher is provided with a preliminary experience with a familiar IR system before using the mediated IR system. Finally, it turned out that the combination of the mediated and combined display seems not ideal for Web searching due to its complexity. In conclusion, this research contributes to a better understanding of how the mediation system and/or the combined display support a Web information user. Results of this research suggest additional research agendas involving both the mediation condition and the display condition for Web IR system design. |
