Hi, i posted this in the urgent maths help forum, but i thought it would be better here, any sort of help would be greatly appreciated, thanks.

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- Apr 24th 2008, 03:22 PMskamoniBias estimators - please help
Hi, i posted this in the urgent maths help forum, but i thought it would be better here, any sort of help would be greatly appreciated, thanks.

- Apr 25th 2008, 04:28 AMmr fantastic
- Apr 25th 2008, 05:18 AMCaptainBlack
An estimator of a parameter is unbiased iff:

You first problem is to determine the value of so that:

is an unbiased estimator for the variance.

This is imposible unless the variance is as the expectation of the right hand side is .

Now if instead it was meant to be:

we have:

This last bit of simplification because the are independently identically distributed.

So:

so can you now tell us what value of will make an unbiased estimator?

RonL - Apr 25th 2008, 06:05 AMskamonithanks
yeh sorry i got the question wrong, you had to include the squared, thanks alot for your help