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
Some keys for interpreting the factorial maps are:
- Points near the origin have undifferentiated profile
distribution as a consequence of the origin being placed at the center of
gravity of both clouds N ( I ) and N ( J ).
- The points, which do not contribute essentially to the inertia
of each axis, are virtually identical to the average profile.
- Points of a cloud (or set) situated away from the origin, but
close to each other have similar profiles
- Geometrically, a particular row profile would be attracted to a
position in its subspace, that corresponds to
column variable categories prominent in that row profile.
- When correspondence analysis has more than two dimensions.
Proximity with one pair of axes may disappear when other axes are (added)
- 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. cannot be interpreted. The joint display
of coordinates shows the relation between a point from one set and all
points of the other set and not between individual points between each
- A point makes a high contribution to the inertia of a principal
axis in two ways –when it has a large distance from the barycenter,
even if it has a small mass, or when it has a large mass, but a small
distance. Considering all these points, it is necessary that the numerical
results of correspondence analysis, viz. mass. Absolute
contribution (CTR) and relative contribution COS2 j are
all taken into account for interpreting the results of correspondence