Spherical Median Axes
本文研究了球面中位数轴的统计性质，包括渐近相对效率，并与传统的主轴估计量进行比较，发现样本球面中位数轴对异常值具有稳健性。
SUMMARY In an earlier paper, Fisher defined the notion of a median direction for data from a unimodal distribution of three-dimensional unit vectors and studied its statistical properties. Corresponding notions of a median axis for bipolar axial or great circle data were also suggested but not analysed. This paper gives a statistical treatment of spherical median axes, including their asymptotic relative efficiencies, and a comparison with the customary principal or polar axis estimators using asymptotic relative efficiencies. The sample spherical median axes enjoy the same sort of resistance to outlying values as do the median vector, spatial median and linear median.