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Concept hierarchy across languages in text-based image retrieval: a user evaluation
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Abstract
The University of Sheffield participated in Interactive ImageCLEF 2005 with a comparative user
evaluation of two interfaces: one displaying search results as a list, the other organizing retrieved images into
a hierarchy of concepts displayed on the interface as an interactive menu. Data was analysed with respect to
effectiveness (number of images retrieved), efficiency (time needed) and user satisfaction (opinions from
questionnaires). Effectiveness and efficiency were calculated at both 5 minutes (CLEF condition) and at final
time. The list was marginally more effective than the menu at 5 minutes (no statistical significance) but the
two were equal at final time showing the menu needs more time to be effectively used. The list was more efficient
at both 5 minutes and final time, although the difference was not statistically significant. Users preferred
the menu (75% vs. 25% for the list) indicating it to be an interesting and engaging feature. An inspection
of the logs showed that 11% of effective terms (i.e. no stop-words, single terms) were not translated and
that another 5% were ill translations. Some of those terms were used by all participants and were fundamental
for some of the tasks. Non translated and ill translated terms negatively affected the search, hierarchy generation
and, results display. More work has to be carried out to test the system under different setting, e.g. using
a dictionary instead of MT that appears to be ineffective in translating users’ queries that rarely are
grammatically correct. The evaluation also indicated directions for a new interface design that allows the user
to check query translation (in both input and output) and that incorporates visual content image retrieval to
improve result organization