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).
