Variable bandwidth and one-step local M-estimator

We study a robust version of local linear regression smoothers augmented with variable bandwidth. The proposed method inherits the advantages of local polynomial regression and overcomes lack of robustness of least-squares techniques. The use of variable bandwidth enhances the flexibility of the resulting local M-estimators and makes them possible to cope well with spatially inhomogeneous curves, heteroscedastic errors and nonuniform design densities. Under appropriate regularity conditions, it ...