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Re: st: higher occurrence of disease X in rare disease Y
From
Doug Hemken <[email protected]>
To
[email protected]
Subject
Re: st: higher occurrence of disease X in rare disease Y
Date
Thu, 05 Dec 2013 08:42:39 -0600
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, "[email protected]" 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
> > [email protected]
> >
> > *
> > * 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.
>
> [email protected]
> 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.
[email protected]
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/