RE: AI-GEOSTATS: Unbaisedness

2006-09-15 Thread Digby Millikan








That’s what I was wondering unbiasedness is based on E(Z*) = the
mean,

But we know Z* is not the mean because we are estimating it. I'm sure

it's true, otherwise E(Z*-Z) = 0 would not be published so many books,

however there is not a lot of explanation of this assumption.

 

pp252 Practical Geostatistics 2000;

 

 " ue = E{g1} - E{T} = u - u = 0 "

 

My question was how is does E{g1} = u, when we know it's value is g1.

Is this unbiasedness an assumption or a reality? An assumption so that

we only have to minimise, the variance, assuming the error distribution

has a zero mean.

 

 

 

Prof. Dr. K. Gerald v.d. Boogaart

 

sum_i w_i E[Z(x_i)] - E[Z(x_0)] =0 

 

But how do you get here:

> 

>   
sumwu - u =0  says all Z(x) =u this is

> not true?

 

 








Re: AI-GEOSTATS: Unbaisedness

2006-09-14 Thread Isobel Clark
No, average of (Z*-Z) is zero  average of (sum wZi - Z i)s zero  sum wi times average of Z - average if Z =0  if sum w = 1 then this is true, otherwise not     Says nothing at all about the average of Z.     OK?  IsobelDigby Millikan <[EMAIL PROTECTED]> wrote:BLUE : “Best Linear Unbiased Estimator”      Best : Minimium error variance.   Linear :   Linear combination of sample values.   Unbiased :  E(Z*-Z) = 0   Estimator:  An estimate      Is unbiasedness a fas? E(Z*-Z) = 0     E(sumwZ(x) – Z) = 0     sumwu – u =0  says all Z(x) =u this is not true?      

AI-GEOSTATS: Unbaisedness

2006-09-14 Thread Digby Millikan








BLUE : “Best Linear Unbiased Estimator”

 

 Best : Minimium
error variance.

 Linear :   Linear
combination of sample values.

 Unbiased :  E(Z*-Z) = 0

 Estimator:  An estimate

 

 Is unbiasedness a fas? E(Z*-Z) = 0

  
E(sumwZ(x) – Z) = 0

  
sumwu – u =0  says all Z(x) =u this is not true?