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# Re: st: Testing equality of odds ratios outside of logistic regression

 From Steve Samuels To statalist@hsphsun2.harvard.edu Subject Re: st: Testing equality of odds ratios outside of logistic regression Date Sun, 9 May 2010 20:18:06 -0400

```Actually Michael M.'s response answers your question, because you did
not ask for a simultaneous test.

Steve

On Sun, May 9, 2010 at 8:16 PM, Steve Samuels <sjsamuels@gmail.com> wrote:
> You can use -logistic- and test the interactions or -cc- with a test
> for homogeneity
>
> *****************
> use http://www.stata-press.com/data/r11/bdesop, clear
> des
> gen tobac20 = tobacco <=2
> xi: logistic case i.tobac20*i.alcohol [fw=freq]
> testparm _ItobXa*
> cc case tobac20 [fw=freq], by(alcohol) bd
> **********************
> or
> On Sun, May 9, 2010 at 7:49 PM, Michael I. Lichter <MLichter@buffalo.edu> wrote:
>> I'm assisting on a paper where we examine the relationship between each of
>> four dichotomous predictors variables and one dichotomous outcome variable.
>> Prediction is our primary objective. The predictors are all measures of more
>> or less the same thing, and we want to know whether, *without controlling
>> for any of the others*, they predict the outcome equally well. We want to be
>> able to say, "If you could only pick one of these variables as a predictor
>> of the outcome, it wouldn't make any difference which one you selected."
>>
>> For each of the predictors we calculate a odds ratio and a corresponding
>> confidence interval. The odds ratios are very similar in magnitude and have
>> confidence intervals that overlap almost entirely. We did not do any formal
>> tests, not knowing of any offhand, and, because this isn't a central point,
>> we didn't think it was very important. When we reported that the odds ratios
>> were essentially equal, a reviewer objected that we had not tested for
>> equality. Any suggestions?
>>
>> In logistic regression, by the way, two of the four variables emerged as
>> significant predictors and two did not, controlling for the others. That is
>> of interest, but it doesn't answer my initial question. At least, I don't
>> think it does.
>> *
>> *   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/
>>
>
>
>
> --
> Steven Samuels
> sjsamuels@gmail.com
> 18 Cantine's Island
> Saugerties NY 12477
> USA
> Voice: 845-246-0774
> Fax:    206-202-4783
>

--
Steven Samuels
sjsamuels@gmail.com
18 Cantine's Island
Saugerties NY 12477
USA
Voice: 845-246-0774
Fax:    206-202-4783

*
*   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/
```