[R] Mean Significance

Liaw, Andy andy_liaw at merck.com
Wed Nov 5 18:57:47 CET 2003

As Prof. Ripley said, the test on contrast is valid only if you selected the
contrast before seeing the data.  Using the same data for both hypothesis
generation and hypothesis confirmation is extremely hazardous!


> From: Igor Roytberg [mailto:ir1982 at u.washington.edu] 
> Hello,
> If you determine the means of x treatments and see that one 
> is larger than the others, can you use a sample normal to 
> determine how statistically significant the difference is? or 
> would contrasts by a better tool? How would one go about to 
> do this in R?
> Thanks for any help (since R is new to me),
> Igor

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