这里的学习模型包括对于估测变量的方差估计，以及股票收益率与这个预测变量的协方差。

The learning model includes the volatility estimation of the predicative variables and the covariance of stock return and this predicative variable.

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针对这一异常现象，本文通过对隐含相关收益率的因素分解，发现其来源于协方差项。

Furthermore, according to decompose the correlation implied returns, the paper find that the "anomalies" results from covariance term of implied returns.

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One more thing, I said they're not independent, so we have to talk about the covariance between the returns.

还有，我说过它们不是相互独立的，因此我们还需要讨论两个收益率的协方差。

耶鲁公开课 - 金融市场课程节选

You take all the risky assets ... and you analyze them first to get their-- you have to do a statistical analysis to get their expected returns, their variances, and their covariances.

你需要对所有的风险资产进行分析,首先要得到它们的-,你必须要做一个统计分析,算出它们的预期收益率，方差，和它们的协方差。

耶鲁公开课 - 金融市场课程节选