Browsing Hierarchical Data with Multi-Level Dynamic Queries and Pruning
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Users often must browse hierarchies with thousands of nodes in search of
those that best match their information needs. The PDQ Tree-browser
(Pruning with Dynamic Queries) visualization tool was specified, designed
and developed for this purpose. This tool presents trees in two
tightly-coupled views, one a detailed view and the other an overview.
Users can use dynamic queries, a method for rapidly filtering data, to
filter nodes at each level of the tree. The dynamic query panels are
user-customizable. Subtrees of unselected nodes are pruned out, leading
to compact views of relevant nodes. Usability testing of the PDQ
Tree-browser, done with 8 subjects, helped assess strengths and identify
possible improvements. The PDQ Tree-browser was used in Network
Management (600 nodes) and UniversityFinder (1100 nodes) applications.
A controlled experiment, with 24 subjects, showed that pruning significantly improved performance speed and subjective user satisfaction. Future research directions are suggested. (Also cross-referenced as CAR-TR-772) (Also cross-referenced as ISR-TR-95-53)