Something is rotten in the state of Denmark
- From: "\"Luis A. Afonso\"" <licas_@xxxxxxxxxxx>
- Date: Fri, 18 Aug 2006 17:32:17 EDT
(corrected : a typo)
As Bob Ling do not put down the expression of the standard deviation he used I have to uncover its value from the Z value, - 0.9542, he gave. ( Aug 16, 2006 11:43 PM).
Because
_______(65/ 161 - 14/ 32) / s = - 0.9542 then
________ s = 0.0354, var = 0.00125
By your reasoning is, I suppose
_______ p´´ = (65+14) / (161 + 42) = 0.38916
_______ a = p`` * (1-p´´) = 0.23771
_______ var = a * ( 1/ 161 + 1/ 32 ) = 0.0089
I´am curious in what it is going on here.
It is important to note that my simulations (THAT ARE INDEPENDENT TO THE EXPRESSIONS ABOVE gave the variance 0.0092 (program vardiff)
Therefore IT IS NOT the Bob Ling´s formula that is right MINE, as the simulations repeatable had shown. Furthermore the difference is a mere 3 to 4 % not the value Bob Ling says.
***Something is rotten in the state of Denmark (Bill Shakespeare).
_____licas (Luis A. Afonso)
.
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