From: Achim Zeileis <Achim.Zeileis_at_wu-wien.ac.at>

Date: Wed 20 Apr 2005 - 05:00:33 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Apr 20 05:08:36 2005

Date: Wed 20 Apr 2005 - 05:00:33 EST

On Wed, 20 Apr 2005 01:36:02 +0800 ronggui wrote:

> it seems that all the existing prop test assume 2 independent or

*> matched sample.but in the real world, many situations are not as we
**> assume.for example,i do a research on the voter's prefernce through a
**> random sampling.and the sample shows that 23% of the sample choose
**> A,28% choose B,the others choose C.and i want to test the diference
**> between the proportion choosing A and B (23%-28%=-5%) is sinificant or
**> just due to sampling error. i think the prop.test is not proper here.
**> and it seems all the stat textbooks do not deal with these problem. is
**> it a igorance in the statistical world or just something else?
*

If I understand you correctly, you're not interested in C at all and
just want to test P(A | C') = P(B | C') = 0.5. This can be done by
binom.test. Assuming the above were not proportions but observations
binom.test(23, 23+28)

Instead of performing this exact test you can also perform the
asymptotic test via prop.test()

prop.test(23, 23+28)

Z

> ______________________________________________

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R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Apr 20 05:08:36 2005

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