  Minimizing the relative inertia of a statistical group with respect to the
inertia of the overall sample defines an unique point, the in-focus, which
constitutes a context-dependent measure of typical group tendency, biased in
comparison to the group centroid. Maximizing the relative inertia yields an
unique out-focal point, polarized in the reverse direction. This mechanism
evokes the relative variability reduction of the outgroup reported in Social
Psychology, and the stereotypic-like behavior of the in-focus, whose bias
vanishes if the outgroup is constituted of a single individual. In this
picture, the out-focus plays the role of an anti-stereotypical position,
identical to the in-focus of the complementary group.
