Computers are able to multiply useless images without taking into account that, by definition, every graphic corresponds to a table. This table allows you to think about three basic questions that go from the particular to the general level. When this last one receives an answer, you have answers for all of them. Understanding means accessing the general level and discovering significant grouping (patterns). Consequently, the function of a graphic is answering the three following questions:

Which are the X,Y, Z components of the data table? (What it’s all about?)

What are the groups in X, in Y that Z builds? (What the information at the general level is?)

What are the exceptions?

Jacques Bertin