Without parametric assumptions, high-dimensional regression
analysis is already complex. This is made even harder when data are subject to
censoring. In this article, we seek ways of reducing the dimensionality of the
regressor before applying nonparametric smoothing techniques. If the censoring
time is independent of the lifetime, then the method of sliced inverse
regression can be applied directly. Otherwise, modification is needed to adjust
for the censoring bias. A key identity leading to the bias correction is
derived and the root-$n$ consistency of the modified estimate is established.
Patterns of censoring can also be studied under a similar dimension reduction
framework. Some simulation results and an applica-tion to a real data set are
reported.