document: Evaluating the effectiveness of search task trails In this paper , we introduce `` task trail '' as a new concept to understand user search behaviors . We define task to be an atomic user information need . Web search logs have been studied mainly at session or query level where users may submit several queries within one task and handle several tasks within one session . Although previous studies have addressed the problem of task identification , little is known about the advantage of using task over session and query for search applications . In this paper , we conduct extensive analyses and comparisons to evaluate the effectiveness of task trails in three search applications : determining user satisfaction , predicting user search interests , and query suggestion . Experiments are conducted on large scale datasets from a commercial search engine . Experimental results show that : ( 1 ) Sessions and queries are not as precise as tasks in determining user satisfaction . ( 2 ) Task trails provide higher web page utilities to users than other sources . ( 3 ) Tasks represent atomic user information needs , and therefore can preserve topic similarity between query pairs . ( 4 ) Task-based query suggestion can provide complementary results to other models . The findings in this paper verify the need to extract task trails from web search logs and suggest potential applications in search and recommendation systems .
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