an analysis of users' query expansion and the degree of match between expanded subject queries with the list of persian subject headings

pupose: this research aims to investigate how users expand their queries when encountered with irrelevant retrievals and through examine the degree of match between users' expanded subject queries and the list of persian subject headings. furthermore, it compares the patterns of query expansion in two subject areas: 1) agriculture (applied sciences); 2) education and psychology (humanities). method: data were collected through observation of the process of query expansion and also through transaction log analysis. results: findings show that in more cases, there is not a significant difference between users' query expansion behavior in the two faculties. in terms of how users expand their queries findings are: 1) users use lexical variable more than contextual variables; 2) users often expand their queries through one change; 3) when users expand their queries, the change in the type of search field happens for general, title, and subject fields.