Diagnostic tools for nearest neighbors techniques when used with satellite imagery

Nearest neighbors techniques are non-parametric approaches to multivariate prediction that are useful for predicting both continuous and categorical forest attribute variables. Although some assumptions underlying nearest neighbor techniques are common to other prediction techniques such as regression, other assumptions are unique to nearest neighbor techniques. Graphical diagnostic tools are proposed to evaluate the assumptions and to address issues of bias, homoscedasticity, influential observations, outliers, and extrapolations. The tools are illustrated using results obtained from applying the k-Nearest Neighbors technique with Landsat imagery and forest inventory ground observations.