Re: [R] confidence intervals on multiple comparisons

From: Bert Gunter <gunter.berton_at_gene.com>
Date: Tue, 15 May 2007 13:21:37 -0700

 

> -----Original Message-----
> From: r-help-bounces_at_stat.math.ethz.ch
> [mailto:r-help-bounces_at_stat.math.ethz.ch] On Behalf Of
> Cody_Hamilton_at_edwards.com
> Sent: Tuesday, May 15, 2007 12:52 PM
> To: Salvatore Enrico Indiogine
> Cc: R-help_at_stat.math.ethz.ch; r-help-bounces_at_stat.math.ethz.ch
> Subject: Re: [R] confidence intervals on multiple comparisons
>
>
> Enrico,
>
> prop.test is for testing proportions two at a time. If you
> want to test
> for differences between 4 proportions simultaneously (rather
> than two at a
> time), try a logistic regression model (from which you can
> get confidence
> intervals for each of your groups).
>
> Cody Hamilton, PhD
> Staff Biostatistician
> Edwards Lifesciences
>

Yes, but beware: in the default contr.treatment coding for contrasts, you get estimates and confidence intervals for the first group and for the **differences** between the first group and the others. As you said, it's easy to get what you want from this, but you must pay attention to the details here.

Bert Gunter
Genentech Nonclinical statistics

>
>
> "Salvatore Enrico
>
> Indiogine"
>
> <hindiogine_at_gmail
> To
> .com>
> R-help_at_stat.math.ethz.ch
> Sent by:
> cc
> r-help-bounces_at_st
>
> at.math.ethz.ch
> Subject
> [R] confidence
> intervals on
> multiple comparisons
>
> 05/13/2007 10:51
>
> AM
>
>
>
>
>
>
>
>
>
>
>
>
>
> Greetings!
>
> I am using prop.test to compare 4 proportions to find out whether they
> are equal. According to the help function you can not have confidence
> intervals if you compare more than 2 proportions.
>
> I need to find an effect size or confidence interval for
> these proportions.
>
> Any suggestions?
>
> Enrico
>
> --
> Enrico Indiogine
>
> Mathematics Education
> Texas A&M University
> hindiogine_at_gmail.com
>
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Tue 15 May 2007 - 20:30:10 GMT

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