Figure 2
From: Dysmorphometrics: the modelling of morphological abnormalities
M-estimators. Different M-estimators (left column) and their outlier influence functions (right column). (a,b) The Quadratic M-estimator, (c,d) The Lorentzian estimator and (e,f) The Truncated Quadratic. The original Quadratic has a linear increasing outlier influence without bound, while both the Lorentzian and the Truncated Quadratic have interesting saturating properties.