Map or Gantt? Which diagram helps viewers best in spatio-temporal data exploration tasks?
Leonie M. Bosveld-De Smet and DaniÃ«l Houben
In this paper we investigate the effectiveness and efficiency of two two-dimensional static visual representations of spatio-temporal data, a map-based and a Gantt-based diagram, in their support of various information retrieval tasks. The map-based diagram is characterized by a natural spatial arrangement of locations on a schematic map. The Gantt-based one represents time naturally as a linearly ordered set of time intervals from left to right. A within-subject empirical experiment has been conducted, in which participants were asked to verify queries about persons, locations, and time intervals. The formulation of the queries was based on (i) Bertin’s three reading levels, (ii) certain cognitive operations, and (iii) different syntactic orders of expressions denoting persons, locations and times. Response correctness and response time were recorded. With respect to response accuracy, both diagrams support viewers well in nearly all information retrieval tasks. Regarding efficiency, the map-based diagram elicited significantly faster response times than the Gantt-based one, except for queries with time in focus. The results suggest that map-based diagrams require less search and reasoning effort of viewers to retrieve the information asked for in the task types used in this study.