Nearest-neighbor variance estimation (NNVE): robust covariance estimation via nearest-neighbor cleaning.

From: Journal of the American Statistical Association | Date: December 1, 2002| Author: Raftery, Adrian E.; Wang, Naisyin | Copyright information

Robust covariance estimation commonly proceeds by downweighting outliers. In this article we measure the "outlyingness" of a data point by the standardized distance between the point and its Kth nearest neighbor. The appropriate weights for robust estimation are found by a model-based mixture modeling approach that follows from considering the data cloud as a realization of a high-dimensional point process. To correct a potential bias when there are no outliers, we introduce a boundary corr...

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