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Re: st: higher occurrence of disease X in rare disease Y


From   Nick Cox <njcoxstata@gmail.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: higher occurrence of disease X in rare disease Y
Date   Thu, 5 Dec 2013 18:54:34 +0000

Say rather that C (largely for Stata) and S (marginally for Stata)
are part of the shared heritage.
Nick
njcoxstata@gmail.com


On 5 December 2013 18:16, Doug Hemken <dehemken@wisc.edu> wrote:
> Thanks, Nick. I see Mata is more R-like than I had appreciated!
>
> On 12/05/13, Nick Cox  wrote:
>> Doug's code is fine and suits the purpose perfectly.
>>
>> A footnote is to underline that Mata can be used to the same "smart
>> calculator" end, e.g.
>>
>> . mata
>> : X = (0..6)'
>> : binomialp(6,X,1/36)
>> 1
>> +---------------+
>> 1 | .8444875698 |
>> 2 | .1447692977 |
>> 3 | .0103406641 |
>> 4 | .0003939301 |
>> 5 | 8.44136e-06 |
>> 6 | 9.64727e-08 |
>> 7 | 4.59394e-10 |
>> +---------------+
>> : binomialp(6,(0..6)',1/36)
>> 1
>> +---------------+
>> 1 | .8444875698 |
>> 2 | .1447692977 |
>> 3 | .0103406641 |
>> 4 | .0003939301 |
>> 5 | 8.44136e-06 |
>> 6 | 9.64727e-08 |
>> 7 | 4.59394e-10 |
>> +---------------+
>>
>>
>> Nick
>> njcoxstata@gmail.com
>>
>>
>> On 5 December 2013 14:42, Doug Hemken <dehemken@wisc.edu> wrote:
>> > Here is a script that illustrates the probabilities using Stata, it is such a small problem that you can illustrate statistical power by trail-and-error:
>> >
>> > set obs 7
>> > gen X = _n - 1
>> > gen prob = binomialp(6,X,1/36)
>> > gen prob10 = binomialp(10,X,1/36)
>> > gen prob12 = binomialp(12,2*X,1/36)
>> >
>> >
>> > On 12/05/13, Doug Hemken wrote:
>> >> If your sample size is literally six cases, then your unconditional probability of seeing disease X is 0.145. If there is no relation between Y and X, it wouldn't be too unusual to see 1 case of X crop up in 6 cases of Y. This is from a binomial distribution.
>> >>
>> >> On 12/05/13, "tiong21@netzero.net" wrote:
>> >> > The prevalence of disease (X) is 1 in 36 in the general population. In a sample population with a very rare disease (Y) of unknown etiology, the prevalence of disease X is 1 in 6 ( ie: 1 case of X was found in the sample population of 6 rare cases of disease Y. How do I show statistically that this higher occurrence of disease X in rare disease Y is not due to chance? And as a corollary suggest that disease X may be a contributory factor in the etiology of disease Y (an issue of causality). Furthermore, should a Poisson distribution be used to calculate the probabilities? A sample Stata script will be much appreciated.
>> >> >
>> >> >
>> >> > Tiong The
>> >> > tiong21@netzero.net
>> >> >
>> >> > *
>> >> > * For searches and help try:
>> >> > * http://www.stata.com/help.cgi?search
>> >> > * http://www.stata.com/support/faqs/resources/statalist-faq/
>> >> > * http://www.ats.ucla.edu/stat/stata/
>> >>
>> >> --
>> >> Doug Hemken
>> >> 4226I Social Science Bldg.
>> >>
>> >> dehemken@wisc.edu
>> >> 262-4327
>> >> *
>> >> * For searches and help try:
>> >> * http://www.stata.com/help.cgi?search
>> >> * http://www.stata.com/support/faqs/resources/statalist-faq/
>> >> * http://www.ats.ucla.edu/stat/stata/
>> >
>> > --
>> > Doug Hemken
>> > 4226I Social Science Bldg.
>> >
>> > dehemken@wisc.edu
>> > 262-4327
>> >
>> > To make a consulting appointment send me an email, or use the on-line scheduler:
>> > https://calendar.wisc.edu/scheduling-assistant/public/profiles/PlRxCykH.html
>> > *
>> > * For searches and help try:
>> > * http://www.stata.com/help.cgi?search
>> > * http://www.stata.com/support/faqs/resources/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/faqs/resources/statalist-faq/
>> * http://www.ats.ucla.edu/stat/stata/
>
> --
> Doug Hemken
> 4226I Social Science Bldg.
>
> dehemken@wisc.edu
> 262-4327
>
> To make a consulting appointment send me an email, or use the on-line scheduler:
> https://calendar.wisc.edu/scheduling-assistant/public/profiles/PlRxCykH.html
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/faqs/resources/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/faqs/resources/statalist-faq/
*   http://www.ats.ucla.edu/stat/stata/


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