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RE: st: how to find the integral for a portion of a normal distribution.


From   "Lachenbruch, Peter" <Peter.Lachenbruch@oregonstate.edu>
To   "'statalist@hsphsun2.harvard.edu'" <statalist@hsphsun2.harvard.edu>
Subject   RE: st: how to find the integral for a portion of a normal distribution.
Date   Tue, 4 May 2010 09:43:37 -0700

This seems to be the expectation of x for x>c.  I used integration by parts and got (DON'T TRUST ME HERE - I haven't done this for a while)
Exp(-.5*((c-mu)/sigma)^2) + mu*P(x>c)

It's simple enough that it feels right.

Tony

Peter A. Lachenbruch
Department of Public Health
Oregon State University
Corvallis, OR 97330
Phone: 541-737-3832
FAX: 541-737-4001


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Buzz Burhans
Sent: Monday, May 03, 2010 8:59 PM
To: statalist@hsphsun2.harvard.edu
Subject: RE: st: how to find the integral for a portion of a normal distribution.

Mike, thanks for your help. Let me try to clarify what I want.  If I have a
trial where average response was 2.05 liters, sd 1.74,  What I want to find
is the cumulative volume of all responses >= 1; and the cumulative volume of
all responses <1  

Is that any clearer?

Thanks


Buzz Burhans, Ph.D. 

Dairy-Tech Group
So. Albany, VT / Twin Falls ID

Phone: 802-755-6842
Cell: 208-320-0829
Fax VT: 802-755-6842
Fax ID: 208-735-1289

Email: buzzb3@earthlink.net

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Hollis,Michael E
Sent: Monday, May 03, 2010 9:36 PM
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: how to find the integral for a portion of a normal
distribution.

I may be missing something here, but can't you simply use the normal  
distribution with mean=proportion z >= some threshold, q=1-p and  
variance p(1-p)/n?  No integration involved.

As I said, I might be missing something!

Sent from my iPhone

On May 3, 2010, at 7:58 PM, "Buzz Burhans" <buzzb3@earthlink.net> wrote:

> of the observations <=1 from
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