CompaRing: Reducing Costs of Visual Comparison

Comparison is a frequent task when analyzing data. In visualization, comparison tasks are naturally carried out based on a visual representation of the data. Visual comparison allows us to gain insight where plain computations of numerical differences alone cannot grasp the complex interdependencies in the data. Yet, visual comparison also comes at a cost. There are costs when interpreting the visual representation and costs when interactively carrying out the comparison. We present techniques to reduce some of the costs associated with visual comparison. We address cognitive costs for comparing objects that are spread across a visual representation and interaction costs for selecting and navigating between objects to be compared. Our techniques are illustrated by the example of comparing geographic regions in choropleth maps.