Exploring Point and Interval Event Patterns: Display Methods and Interactive Visual Query

Fig. 1: The EventFlow display including the control panel and legend (left), the aggregated record display (middle), and the individual record display (right). Abstract— Our work on searching point-based event sequences with the Align, Rank, Filter, and Summary concepts produced a powerful tool (Lifelines2) that is being applied in an increasing set of medical and other applications. The LifeFlow aggregation tool expanded the capabilities of Lifelines2 to show common patterns of events on a single-screen display, resulting in the ability to summarize millions of individual patient records. However, users found that point-based event sequences limited their capacity to solve problems that had inherently interval attributes, for example, the 3-month interval during which patients took a medication. This paper reports on our development of EventFlow, an application that integrates interval-based events into the original LifeFlow mechanisms. Interval events represent a fundamental increase in complexity at every level of the application, from the input and data structure to the eventual questions that a user might ask of the data. Our goal was to accomplish this integration in a way that appeared to users as a simple and intuitive extension of the original LifeFlow tool. In this paper, we present novel solutions for displaying interval events, simplifying their visual impact, and incorporating them into meaningful queries. Index Terms—EventFlow, temporal event sequence, temporal event querying.