Nonparametric estimation of the Bayes risk

using a

-nearest-neighbor (

-NN) approach is investigated. Estimates of the conditional Bayes error

for use in an unclassified test sample approach to estimate

are derived using maximum-likelihood estimation techniques. By using the volume information as well as the class representations of the

-NN\´s to

, the mean-squared error of the conditional Bayes error estimate is reduced significantly. Simulations are presented to indicate the performance of the estimates using unclassified testing samples.