[R] suggestion for proportions

Bert Gunter gunter.berton at gene.com
Wed Sep 7 15:34:11 CEST 2011


Please! ...  ?prop.test

not t tests.

-- Bert

-- 

On Wed, Sep 7, 2011 at 4:21 AM, John Sorkin <JSorkin at grecc.umaryland.edu> wrote:
> >From you description, you should not used a paired Student's t-test. One uses a paired test when pairs of observations come from the same experimental unit (and thus are correlated). You describe a study where each experimental unit is tested once and where there are two independent groups of experimental units. Look at t.test (i.e. enter ?t.test).
> John
>
> John David Sorkin M.D., Ph.D.
> Chief, Biostatistics and Informatics
> University of Maryland School of Medicine Division of Gerontology
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
> (Phone) 410-605-7119
> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>
>>>> array chip <arrayprofile at yahoo.com> 9/7/2011 4:11 AM >>>
> Hi, I am wondering if anyone can suggest how to test the equality of 2 proportions. The caveat here is that the 2 proportions were calculated from the same number of samples using 2 different tests. So essentially we are comparing 2 accuracy rates from same, say 100, samples. I think this is like a paired test, but don't know if really we need to consider the "paired" nature of the data, and if yes then how? Or just use prop.test() to compare 2 proportions?
>
> Any suggestion would be greatly appreciated.
>
> Thanks
>
> John
>
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-- 
"Men by nature long to get on to the ultimate truths, and will often
be impatient with elementary studies or fight shy of them. If it were
possible to reach the ultimate truths without the elementary studies
usually prefixed to them, these would not be preparatory studies but
superfluous diversions."

-- Maimonides (1135-1204)

Bert Gunter
Genentech Nonclinical Biostatistics



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