An evaluation of a visual analytics prototype for calendar-related spatiotemporal periodicity detection and analysis

Whether it is sunrise, the weekend, or Christmas, some form of temporal structure or periodic pattern governs our daily activities. Understanding them is essential to making sense of human activity, because they frame normality and allow us to identify abnormalities. However, cultural heterogeneity and scale greatly complicate our ability to uncover and understand human activity at a given time within a region. Current research in the field of visual analytics and geography provide methods of addressing spatiotemporal periodicity, but they fall short in providing access to multiple spatial and temporal scales via a relevant calendar. In response to these shortcomings, we developed PerSE (periodicity in spatiotemporal events), a coordinated-view Web application designed to aid users in the detection and analysis of calendar-related periodicity in spatiotemporal event data sets. Given the complexity of such a visualization tool, this paper focuses on the usability and learnability of PerSE. We evaluated the tool through a 20-participant study that consisted of training, a multiple-choice test, and the System Usability Scale. Our analysis of the results shows that the complex combination of visual tools and multi-scale, multi-calendar capability used within PerSE is effective, but still in need of usability improvements.