母体，随机样本。样本统计， 样本平均数和变异数的动差。

Populations, random samples. Sample statistics, moments of the sample mean and variance.

youdao

然而，这些方法都是根据样本的变异数或报酬的共变异数估算的估计值。

However, these methods are estimated according to sample variance and covariance estimators of returns.

youdao

然而，这些方法都是根据样本的变异数或报酬的共变异数估算的估计值。

However, these methods are estimated according to sample variance and covariance estimators of returns.

youdao