Schmerling S, Peil J
Gegenbaurs Morphol Jahrb. 1986;132(1):29-35.
The kernel estimation of an unknown density function derived from measured values has at least one disadvantage: the second central moment of the estimated density is greater than the sample variance. This is unsatisfactory. It is possible to reduce the difference between both variances by an improvement of the method of kernel estimation. But for improved GAUSS-kernels it is not possible to reduce it to zero.
估计密度的二阶中心矩大于样本方差。这是不令人满意的。通过改进核估计方法有可能减小两者方差之间的差异。但是对于改进的高斯核,不可能将其减小到零。