6.5.6 Outlier points

Outlier points plague correspondence analysis. Occasionally, a row or column profile is rare in its set of points that it has a minor role in the determination of the higher order axes. This situation can be discerned easily by considering the point’s contribution to the axes. When a point has a large contribution (CTR) at a large principal coordinate at a major principal axis. Outlier points should be treated as supplementary variables.