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# Re: st: Comparing multiple sample proportions to population proportions

 From Zoe Hyde To statalist@hsphsun2.harvard.edu Subject Re: st: Comparing multiple sample proportions to population proportions Date Fri, 16 Sep 2011 14:24:29 +0800

```Thanks, that's exactly what I need.

Zoe.

On Thu, Sep 15, 2011 at 06:50:02AM -0400, Austin Nichols wrote:
> Zoe Hyde <junk@hobbes.kittybutler.org>:
> findit mgof
>
> On Thu, Sep 15, 2011 at 3:54 AM, Zoe Hyde <junk@hobbes.kittybutler.org> wrote:
> > Hi Everyone,
> >
> > I know that I can compare a sample proportion to a population proportion
> > with either a one-sample Z test or a binomial probability test.
> >
> > e.g., to see if the proportion of drug use in my sample is different to
> > the proportion in the population (16.2%):
> >
> >
> > prtest drug_use == 0.162
> > OR
> > bitest drug_use == 0.162
> >
> >
> > However, I'm wondering what I should do when I have multiple categories.
> >
> > For example, let's say I have a variable that records smoking status:
> >
> >
> > tab smoke
> >
> >      smoke |      Freq.     Percent        Cum.
> > ------------+-----------------------------------
> >    Current |         11       22.00       22.00
> >  Ex-smoker |         12       24.00       46.00
> >      Never |         27       54.00      100.00
> > ------------+-----------------------------------
> >      Total |         50      100.00
> >
> >
> > I would like to compare these proportions against proprtions
> > for the general population, but it seems wrong to do three tests
> > (sort of like doing a bunch of Mann Whitney U tests without first
> > seeing if a Kruskal-Wallis is significant):
> >
> >
> > bitesti 50 0.22 0.172
> > bitesti 50 0.24 0.285
> > bitesti 50 0.54 0.543
> >
> >
> > So, I'm wondering what I should do?  What would be the correct way to
> > see if smoking status in my sample is different from the general
> > population?
> >
> >
> > Thanks,
> >
> > Zoe.
>
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```