Journal Article

Fast Computation of Tukey Trimmed Regions and Median in Dimension p > 2

Mozharovskyi, Pavlo, Mosler, Karl, Liu, Xiaohui

2019

Overview

Given data in , a Tukey κ-trimmed region is the set of all points that have at least Tukey depth κ w.r.t. the data. As they are visual, affine equivariant and robust, Tukey regions are useful tools in nonparametric multivariate analysis. While these regions are easily defined and interpreted, their practical use in applications has been impeded so far by the lack of efficient computational procedures in dimension p > 2. We construct two novel algorithms to compute a Tukey κ-trimmed region, a naïve one and a more sophisticated one that is much faster than known algorithms. Further, a strict bound on the number of facets of a Tukey region is derived. In a large simulation study the novel fast algorithm is compared with the naïve one, which is slower and by construction exact, yielding in every case the same correct results. Finally, the approach is extended to an algorithm that calculates the innermost Tukey region and its barycenter, the Tukey median. Supplementary materials for this article are available online.

• Publisher: Taylor & Francis,American Statistical Association, the Institute of Mathematical Statistics, and the Interface Foundation of North America,Taylor & Francis Ltd
• Subject: Algorithms / Center of gravity / Computational geometry / Computer simulation / Depth contours / Depth regions / Halfspace depth / Location depth / Multivariate analysis / R-package TukeyRegion / Statistics / Tukey depth / Tukey median / Visualization, Communication, and Evidence