# Mean and Variance of estimators

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#### fed2

##### Active Member
I don't know ho to find mean and variance without numerical sample...
Have you been given some examples of how to do that?

#### fed2

##### Active Member
If you are being asked "What can you say about the unbiasedness, consistency and efficiency of these three estimators?" you must have seen the "E(.)", ie expectation or something. Use that.

If this all is not ringing bell, I wuld just drop the class, and go back-packing or something fun.

#### Lorenzo RU

##### New Member
If you are being asked "What can you say about the unbiasedness, consistency and efficiency of these three estimators?" you must have seen the "E(.)", ie expectation or something. Use that.

If this all is not ringing bell, I wuld just drop the class, and go back-packing or something fun.
Dear fed2,
I know that I have to use the expected value to calculate the means, but I don’t know how to do it in this case (without sample)

#### Dason

##### Ambassador to the humans
Is there a chapter in your textbook that goes along with this section of the course?

#### Lorenzo RU

##### New Member
The problem is that we only had one lesson, and it was useless to solve this exercises