Notice: On March 31, it was announced that Statalist is moving from an email list to a forum. The old list will shut down on April 23, and its replacement, statalist.org is already up and running.

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

 From "Buzz Burhans" To Subject RE: st: how to find the integral for a portion of a normal distribution. Date Mon, 3 May 2010 22:52:44 -0600

```This gets me what I want, but there should be an easier way to express this
as 2 equations?

clear
drawnorm x , means(2.05) sds(1.74) n(100000) clear
sort x
egen lowresponse = total(x) if _n < (100000*.273)
egen highresponse = total(x) if _n >= (100000*.273)
l in 1/50
l in -60/l

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

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of David Muller
Sent: Monday, May 03, 2010 10:26 PM
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: how to find the integral for a portion of a normal
distribution.

To expand upon Michael's suggestion, -display normal((1 - 2.05)/1.74)-
will give you the proportion of responses <=1, and -display 1 -
normal((1 - 2.05)/1.74)- will give you the proportion of responses
>=1.

Note that assuming this normal model for your response you would
expect a little over 10% of your responses to be less than 0, which
positive.

David

On Tue, May 4, 2010 at 2:01 PM, Hollis,Michael E <mhollis@mwdh2o.com> wrote:
> ...you'll then be able to use the standard normal distribution with mean
> zero and unit variance.
>
> Sent from my iPhone
>
> On May 3, 2010, at 8:49 PM, "Buzz Burhans" <buzzb3@earthlink.net> wrote:
>
>> Doesn't your suggestion fit only if the curve is standard normal?, i.e.
>> mean
>> 0, SD 1?
>>
>> Perhaps my use of integral is incorrect; what I want is the area under
the
>> curve of a normal distribution, mean 2.05, sd 1.75 for the portion >=
>> threshold =1, and then the portion < 1
>>
>> Buzz
>>
>>
>> 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
>>
>> .ucla.edu/stat/stata/
>>
>> *
>> *   For searches and help try:
>> *   http://www.stata.com/help.cgi?search
>> *   http://www.stata.com/support/statalist/faq
>> *   http://www.ats.ucla.edu/stat/stata/
>
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/
>

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```