The expressiveness & effectiveness criteria

Mackinlay developed the expressiveness and effectiveness critera for his APT (A Presentation Tool). He described a visualization as expressive if a visualization encodes all relevant informations and only that information. That means that the scientist may see all information s/he wants to examine. Artifacts will be excluded with expressive visualizations.

The effectiveness criteria means that all information is presented clearly. This excludes cluttered screens.

These criteria have been refined by other scientists. Beshers & Feiner use a modified criteria in their AutoVisual system, which is based on Mackinlay's expressiveness and effectiveness. They called it potential expressiveness and potential effectiveness. A visualization is potentially expressive, if it has the potential, under user control, to display all its assigned information over time. It is potentially effective, if over time it can present the information sufficiently clearly. These extensions become necessary for interactive systems. [BES93]

Furthermore Ignatius & Senay describe an extended version of these criteria under consideration of perceptual properties. They encode these modified criteria in their system VISTA. Examples of the perception rules are: "Position is more effectively perceived than color"; "The visual perception system is better attuned to quantitative understanding by using geometry rather than color; "It is not always obvious whether a local extremum is a minimum or a maximum, so the viewers have to figure it out." [SEN94]

Visualization Concepts