Guest Editors' Introduction: Discovering the Unexpected

The marriage of computation, visual representation, and interactive thinking supports intensive analysis. The goal is not only to permit users to detect expected events, such as might be predicted by models, but also to help users discover the unexpected—the surprising anomalies, changes, patterns, and relationships that are then examined and assessed to develop new insight. The Guest Editors discuss the key issues and challenges associated with discovering the unexpected, as well as introduce the articles that make up this Special Issue.