Abstract
Stochastic approximation aims to estimate efficiently level crossing or extermal points of a nonparametric regression function in a parametric or nonparametric manner. For bundle strength of parallel filaments (with stochastic length, cross section etc.,) and in some other problems, one has an extended statistical functional where ψ is a suitable function and G(x|y) stands for a conditional distribution function of X, the dependent variate, given the independent variate Y=y. For a compact set C chosen from extraneous considerations, the problem of interest is to locate an optimal y0∊C, in the sense that . Nonparametric estimation of the conditional distribution G(.|y), nonlinear nature of the functional θ(·), and the fact that y is in continuum in C add complexity to possible statistical resolutions and create impasses for a direct application of the well known Bechhofer-Gupta-Sobel methodology. General asympotics for the selection procedures arising in this context are considered with due emphasis on a stochatic iteration scheme.