Relevance judges' understanding of topical relevance types: An explication of an enriched concept of topical relevance

Despite the centrality of topical relevance in information retrieval system design and evaluation, understanding and implementation of it is usually limited to "direct overall topical matching" between the subject of the query and the subject of the document. The underlying assumption is that only a single type of topical relationship is involved. In related work, a relevance judgment instrument was developed for the Multilingual Access to Large Spoken ArCHives project (MALACH). It incorporates the five topical relevance types (direct relevance, indirect/circumstantial relevance, context relevance, comparison relevance, and pointer relevance) and was applied by four judges to items in the MALACH test collection in Summer 2003. This paper reports on the experiences and perceptions of the judges making more nuanced judgments about topical relevance. The results suggest that more than only one variable/dimension, "whether it is on topic" as usually referred to, contributes to topical relevance, and more than a single topical relationship type, "direct matching" as generally assumed, play an important role in topical relevance.