这是因为当增加回答选项时，就增加了方差值的数目 — (观察值 - 期望值) 2 — 您可以求它的总数。

This is because as you add response options, you increase the number of squared difference scores -- (Observed - Expected)2 -- you can sum over.

youdao

期望值越高越好,方差就相反,因为方差代表着风险,也就是不确定性

Expected value is good and variance is bad because that's risk; that's uncertainty.

youdao

随机变量的方差衡量随机变量值与期望值偏离的程度。

The variance of a random variable measures how far from the expected value its values typically are.

youdao

Expected value is good and variance is bad because that's risk; that's uncertainty.

期望值越高越好,方差就相反,因为方差代表着风险,也就是不确定性

耶鲁公开课 - 金融市场课程节选

But, I've dropped that assumption and now I'm going on to assuming that they're taking account of their dependence on each other, taking account of their different expected returns, and taking account of their different covariances and variances; so that's what we've got.

不过我已经放弃了那个假定,我现在假定,我们需要考虑它们彼此间的相关性，它们有着不同期望收益，不同的协方差和方差;,这是我们所学到的。

耶鲁公开课 - 金融市场课程节选

I don't find that my analysis is profound in the final answer, I just took some estimates using my data and, again, we could-- if someone wanted to argue with us they could argue with my estimates of the expected returns of the standard deviations and the covariances, but not with this theory.

我在计算过程中并没有做太深入的分析，我只是用我的数据做了一下大概的估计,我再说一次，我们可以-,如果有人想就这个问题与我们争辩,他们可以争论我对期望收益的估计,或是争论标准差和协方差的估计值，但并不会针对理论本身。

耶鲁公开课 - 金融市场课程节选