Evacuation traces mini challenge: User testing to obtain consensus discovering the terrorist

The adoption of visual analytics methodologies in security applications is an approach that could lead to interesting results. Usually, the data that has to be analyzed finds in a graphical representation its preferred nature, such as spatial or temporal relationships. Due to the nature of these applications, it is very important that key-details are made easy to identify. In the context of the VAST 2008 Challenge, we developed a visualization tool that graphically displays the movement of 82 employees of the Miami Department of Health (USA). We also asked 13 users to identify potential suspects and observe what happened during an evacuation of the building caused by an explosion. In this paper we explain the results of the user testing we conducted and how the users interpreted the event taken into account.