Data Visualization

We have seen that the graph type that is the most useful cannot be completely derived from the characteristics of the data. The message of the graphical presentation should first be identified in order to make sure that the graph matches the goal of the user. As discovered earlier the goal of the user depends on the phase in the decision process and the state of the data. Furthermore, each graphical technique is linked to the effectiveness of the perception of an observer (Mackinlay, 1986).

Effectiveness criteria for data visualization

According to research performed by Cleveland and McGill there is a difference in the accuracy in quantitative, ordinal and nominal tasks (Mackinlay, 1986). Higher tasks are accomplished more accurately than lower tasks. Tasks to perceive different positions rank as best and differences in shapes are the perceived as being the worst.

Criteria of expressiveness of the data

Variations that should be used for designing expressive graphs and satisfying the users information needs, should at least consider the following data characteristics (Roth and Mattis, 1998b):