A search tactic is a set of search moves that are temporally and semantically related. The current study examined the tactics of medical students searching a factual database in microbiology. The students answered problems and searched the database on three occasions over a 9-month period. Their search moves were analyzed in terms of the changes in search terms used from one cycle to the next, using two different analysis methods.Common patterns were found in the students' search tactics; the most common approach was the specification of a concept, followed by the addition of one or more concepts, gradually narrowing the retrieved set before it was displayed. It was also found that the search tactics changed over time as the students' domain knowledge changed. These results have important implications for designers in developing systems that will support users' preferred ways of formulating searches. In addition, the research methods used (the coding scheme and the two data analysis methods-zero-order state transition matrices and maximal repeating patterns [MRP] analysis) are discussed in terms of their validity in future studies of search tactics.
IntroductionWhen conducting an online search, a searcher enters one or more terms, gets a response from the system, and iteratively modifies the terms until satisfied with the results. Each iteration in the search formulation and reformulation process can be considered a search move. One way to examine these moves is to focus on the search terms selected in each iteration, as suggested by Shute and Smith (1993). For example, one move might consist of the substitution of a narrower term representing the same concept as that searched in the prior move (e.g., the first move might be a search on the term "reference works" and the second move might be a search on the term "encyclopedias").A set of moves that are temporally and semantically related can be a search tactic. While significant work has examined the individual moves that searchers make (Bates, 1979(Bates, , 1987Fidel, 1985), it is equally important to examine the sequences of moves made by searchers in order to understand the cognitive processes they use in formulating and reformulating their searches. The current paper attacks this problem by examining the tactics of medical students searching a factual database in microbiology, focusing on changes in students' tactics as their domain knowledge (i.e., their knowledge in the domain of microbiology) changed over time. In addition, it makes a methodological contribution by comparing two different methods for analyzing sequences of search moves.