A taxonomy of tasks for guiding the evaluation of multidimensional visualizations

The design of multidimensional visualization techniques is based on the assumption that a graphical representation of a large dataset can give more insight to a user, by providing him/her a more intuitive support in the process of exploiting data. When developing a visualization technique, the analytic and exploratory tasks that a user might need or want to perform on the data should guide the choice of the visual and interaction metaphors implemented by the technique. Usability testing of visualization techniques also needs the definition of users' tasks. The identification and understanding of the nature of the users' tasks in the process of acquiring knowledge from visual representations of data is a recent branch in information visualization research. Some works have proposed taxonomies to organize tasks that a visualization technique should support. This paper proposes a taxonomy of visualization tasks, based on existing taxonomies as well as on the observation of users performing exploratory tasks in a multidimensional data set using two different visualization techniques, Parallel Coordinates and RadViz. Different scenarios involving low-level tasks were estimated for the completion of some high-level tasks, and they were compared to the scenarios observed during the users' experiments.