M matrix of a linear regression M-estimator of Mallows type.
MmatrM(x, y, beta, sigma, t.c = 1.345, weights = 1)
matrix of explanatory variables
vector of dependent variables
vector of parameters
robust scale estimate
tuning constant c for Huber's psi-function
vector of robustness weights controlling for the leverage effects
M matrix for the sandwich formula.
Computes the M matrix of the M-estimator of Mallows type. In current implementation only the Huber score function is available.