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Topic: Help with probability&stat problem
Replies: 47   Last Post: Jun 16, 2007 4:32 AM

 Messages: [ Previous | Next ]
 Jack Tomsky Posts: 1,835 Registered: 12/18/04
Re: FALSIFICATION
Posted: Jun 13, 2007 12:59 PM

> Follow-up, in SHORT, the continuity correction leads
> to better results:
> ______With C.C._____EXACT_______Without C.C.
> ______0.00144______0.00156________0.00212____
> Diff___0.00012_____________________0.00056____

I was correcting your arithmetic. The actual result with CC is 0.00306, leading to a difference of 0.00306-0.00156 = 0.00150, which is even worse than the 0.00056 error without the CC.

>
> ***************
> See my post Jun 13, 2007, 7:29 AM. And APPRECIATE
> that Jack Tomsky DID FALSIFY my evaluation
>
> I WROTE (ipsis verbis, please check):
> Date: Jun 13, 2007 7:29 AM
> Author: Luis A. Afonso
> Subject: Re: Help with probability&stat problem
>
> EXACT : p(X<=10) = 0.00156
> Normal Approximation
> *** Without C.C.
> Z = (10 - 22)/sqrt(0.2*0.8*110) = -22/ 4.1952 =
> -2.8604.
> ________________ F(Z) = 0.00212
> *** With C.C.
> ________Z = (10 - 22 + 0.5)/ 4.1952 = -2.9796
> ________________________ F(Z) = 0.00144

Do we agree that 10-22+0.5 = -11.5? Do we agree that -11.5/4.1952 = -2.7412? Do we agree that F(-2.7412) = 0.003061?

I thought that you would appreciate that I was able to check out your calculations and correct the arithmetic. Or was it your BASIC program which did the miscalculation?

If the normal distribution used for the approximation has a smaller mean of 21.5 instead of 22, then the cdf must be larger for all x. So it should have been a red flag that you would get a smaller estimate with the CC than without the CC.

Jack

> The differences approx-EXACT are respectively
>
> _______Without = +0.00056
> _______With C.C. = -0.00012.
> ********
>
> Jack´s response:
>
> The exact probablity calculated from the binomial
> distribution is 0.0015595. The Afonso normal
> approximation is 0.002115. The "improved" Afonso
> normal approximation with a correction factor is
> 0.003061, which is worse. Jack
>
> *******************************
> Licas

Date Subject Author
6/11/07 tutorny
6/11/07 briggs@encompasserve.org
6/11/07 tutorny
6/11/07 Randy Poe
6/11/07 tutorny
6/11/07 Bruce Weaver
6/11/07 tutorny
6/11/07 Bruce Weaver
6/11/07 C6L1V@shaw.ca
6/11/07 Randy Poe
6/11/07 tutorny
6/11/07 Nick
6/11/07 Jack Tomsky
6/11/07 Luis A. Afonso
6/11/07 Jack Tomsky
6/11/07 Luis A. Afonso
6/11/07 Jack Tomsky
6/12/07 Luis A. Afonso
6/12/07 Jack Tomsky
6/12/07 Luis A. Afonso
6/12/07 Jack Tomsky
6/12/07 Luis A. Afonso
6/13/07 Jack Tomsky
6/13/07 Luis A. Afonso
6/13/07 Anon.
6/13/07 Jack Tomsky
6/13/07 Jack Tomsky
6/13/07 Luis A. Afonso
6/13/07 Jack Tomsky
6/13/07 Anon.
6/13/07 Luis A. Afonso
6/13/07 Jack Tomsky
6/13/07 Jack Tomsky
6/13/07 Anon.
6/13/07 Luis A. Afonso
6/13/07 Jack Tomsky
6/13/07 Luis A. Afonso
6/13/07 Jack Tomsky
6/14/07 Luis A. Afonso
6/14/07 Luis A. Afonso
6/14/07 Jack Tomsky
6/14/07 Luis A. Afonso
6/15/07 Luis A. Afonso
6/15/07 Jack Tomsky
6/15/07 Luis A. Afonso
6/15/07 Jack Tomsky
6/15/07 Luis A. Afonso
6/16/07 Luis A. Afonso