Hi, 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 = "quad")). 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