H.3 [Information Storage and Retrieval]: H.3.1 Content Analysis and Indexing; H.3.3 Information Search and Retrieval; H.4 [Information Systems Applications]: H.4.m Miscellaneous SICS has participated in this year's iCLEF cycle mainly with an eye on future experimental settings to work on measurement of searcher trust and con dence in the search process and its results, in keeping with previous experimental studies performed at SICS [2, e.g.]. SICS has used the Flickling interface [1] and the logs delivered by it to study how searcher actions can be interpreted as exponents of user con dence. Variables under consideration for this purpose can be indirect, such as length of interaction, time spent on query formulation, and other measures which require non-trivial interpretation during the analysis phase. Other variables can be more direct, in that they more clearly indicate competence or con dence on the part of the searcher, such as observed edits and additions made to the user dictionaries by the searcher or the number of times a query is reformulated. A con dent searcher can be assumed to be more likely to enter edits into the user dictionary and not to reformulate queries to the same extent. In Table 1 such measures are tabulated, with a distinction between sequences of actions that ultimately provide a successfully identi ed target image and sequences which terminate by the searcher giving up requesting another target. Both the given measures are statistically signi cant.
Successful searches Unsuccessful searches
Number of adds to dictionary 0.092 0.085
Ratio of reformulated queries 0.47 0.35
For next year's cycle we will suggest more explicit measures of user con dence, as well as a task which better teases out di erences between users' task termination decisions.