Maximizing the Variance of $M$-Estimators Using the Generalized Method of Moment Spaces

Abstract

The problem considered is that of optimizing a function of a finite number of linear functionals over an infinite dimensional convex set $S$. It is shown that under some reasonably general conditions the method of moment spaces can be used to reduce the problem to one of optimizing over a simple finite dimensional set (generally a set of convex combinations of extreme points of $S$). The results are applied to finding the maximum asymptotic variance of M-estimators over classes of distributions arising in the theory of robust estimation.