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| From | mai7777 <mai7777@gmail.com> |
| To | statalist@hsphsun2.harvard.edu |
| Subject | Re: st: chi2 on aggregate results |
| Date | Mon, 10 May 2010 14:13:51 -0400 |
Interesting. So if the tabi test is for the independence of the row & column vars, how can I test that the proportions are statistically different given the sample sizes? On Mon, May 10, 2010 at 1:31 PM, Nick Cox <n.j.cox@durham.ac.uk> wrote: > No; it is not. 47.22 and 76.67 are observed column percents, and not predictions of the hypothesis. > > The hypothesis being tested is that the row and column variables are independent. This may be clearer if you also use the -expected- option of -tabi-. > > Nick > n.j.cox@durham.ac.uk > > mai7777 > > Thanks for the quick response. I guess it was the "col" option that I > was looking for, but just to confirm: Below, is the Pearson chi2(1) = > 5.9421 Pr = testing the hypothesis that the proportion of 76.67 in > a sample size of 30 equal to the proportion of 47.22 in a sample size > of 36? > > > . tabi 23 17 \ 7 19, chi col > | col > row | 1 2 | Total > -----------+----------------------+---------- > 1 | 23 17 | 40 > | 76.67 47.22 | 60.61 > -----------+----------------------+---------- > 2 | 7 19 | 26 > | 23.33 52.78 | 39.39 > -----------+----------------------+---------- > Total | 30 36 | 66 > | 100.00 100.00 | 100.00 > > Pearson chi2(1) = 5.9421 Pr = 0.015 > > > On Mon, May 10, 2010 at 1:15 PM, Alan Neustadtl > <alan.neustadtl@gmail.com> wrote: >> Are you looking for something like this? >> >> - tabi 23 17 \ 7 19, chi col - >> >> >> >> On Mon, May 10, 2010 at 1:08 PM, mai7777 <mai7777@gmail.com> wrote: >>> hi, >>> I'm trying to conduct a chi2 on aggregate results to test that the >>> proportions of incidence across two treatments are the same: >>> >>> Treatment 1 has a total of 30 subjects, 23 of which had incidence >>> Treatment 2 has a total of 36 subjects, 17 of which had incidence. > > * > * 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/