[R] Cochran-Armitage

mailbox@fontaine.net delphine at fontaine.net
Fri May 25 14:19:52 CEST 2007

I have to calculate a Cochran-Armitage test on data. I don't know much 
on this test and then, I have few questions on the independence_test 
function. I have read the help and search the archives but this doesn't 
help me...
- They are two ways: either with a formula (independence_test(tumor ~ 
dose, data = lungtumor, teststat = "quad")) or with a table 
(independence_test(table(lungtumor$dose, lungtumor$tumor), teststat = 
Why this difference ? The two ways do not give the same results... Why 
- In the teststat option, what is the difference between "quad", "max" 
and "scalar" ? What is used generaly ?
- Why choosing approximate or asymptotic distribution if an exact test 
can be calculate ?
For a classical Cochran Armitage test (nothing special was specified 
so I guess I have to do the most classical Cochran Armitage test), 
which options should I use ?
Thanks for your help.
Delphine Fontaine

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