6.5.7 Graphics

As in principal components analysis, the results of correspondence analysis are presented on graphs that represent the configurations of points in projection planes, formed by the first principal axes taken two at a time. It is customary to summarize the row and column coordinates in a single plot. However, it is important to remember that in such plots, one can only interpret the distances between row points, and the distances between column points, but not the distances between row points and column points. However, it is legitimate to interpret the relative positions of one point of one set with respect to all the points of the other set

The joint display of row and column points shows the relation between a point from one set and all points of another set, not between individual points between each set. Except in special cases, it is extremely dangerous to interpret the proximity of two points corresponding to different sets of points.

Some keys for interpreting the factorial maps are: