Thread: unbias estimates and variance?

consider the unbias estimaters mu1hat = 1/2 xbar + 1/2 ybar. and mu2hates = 1/3 xbar + 2/3 ybar. calculate the variance of mu1hat and mu2hats

can you work out ?

if so, you can use:


which will give you and hence

repeat the process to get


Finally, you can use:


to get the variance of the sum.

I would like to know a lot more information,
such as the sample sizes, the covariance between the X's and Y's
the variance of X and also of Y

AND I guess, both the expected value of the X and Y is this mythical Moo.

Originally Posted by SpringFan25

can you work out ?

if so, you can use:


which will give you and hence

repeat the process to get


Finally, you can use:


to get the variance of the sum.

i have never herd this one it is nt in my sylabus

covarance is also not in my sylabus and i dont know any resource i cn find to find this one out.. i looked on many website and i not find ...

also there is not muhat 1 and muhat 2. .. it is muonehat and mutwo hats. like U '',

Originally Posted by matheagle

I would like to know a lot more information,
such as the sample sizes, the covariance between the X's and Y's
the variance of X and also of Y

yes so would i

but is not given

and yes the expected valuees are mu
as u obviously were able to figure this without me saying so my omision is justify

Originally Posted by Caption12

consider the unbias estimaters mu1hat = 1/2 xbar + 1/2 ybar. and mu2hates = 1/3 xbar + 2/3 ybar. calculate the variance of mu1hat and mu2hats

and who does moo hates? hates two? moo2hater? moohatter? madhatter?
I'm confused.