Effectiveness of Clustering in Ad-Hoc Retrieval

In this paper, we describe the experiment underlying the CLARITECH entries in the TREC-7 Ad Hoc Retrieval Track. Based on past results, we have come to regard accurate, selective relevance feedback as the dominant factor in effective retrieval. We hypothesized that a clustered rather than a ranked presentation of documents would facilitate judgments of document relevance, allowing a user to judge more documents accurately in a given period of time. This in turn should yield better feedback performance and ultimately better retrieval results. We found that users were indeed able to find more relevant documents in the same time period when results were clustered rather than ranked. Retrieval results from the cluster run were better than results from the ranked run, and those from a combined run were better still. The difference between the ranked and combined runs was statistically significant for both recall and average precision.