I want to make sure that my understanding of the difference between estimator and expectation is right.Expectation is the true mean as we draw a great number of random sample to figure it out.While,the estimator is a mean as well,but it is not a true mean as the not sufficient number of random sample I have framed.这英文是我自己的，我懒得换成中文。

I want to make sure that my understanding of the difference between estimator and expectation is right.
Expectation is the true mean as we draw a great number of random sample to figure it out.
While,the estimator is a mean as well,but it is not a true mean as the not sufficient number of random sample I have framed.
这英文是我自己的，我懒得换成中文。