On 06/03/2010 11:32 AM, Joris Meys wrote:
You're right, it is the same. using I() won't work for the same reason sqrt
don't, so :
x2<- x^2
lrm(y~x+x2)
Thx for the correction.
Cheers
Joris
On Thu, Jun 3, 2010 at 6:14 PM, Bert Gunter<gunter.ber...@gene.com> wrote:
Below. -- Bert
Bert Gunter
Genentech Nonclinical Biostatistics
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But you wrote linear+ square. Don't you mean:
lrm(Y~x+x^2)
--- I believe this is the same as lrm(Y ~ x).
You must protect the x^2 via
lrm(Y ~ x + I(x^2))
But don't use that construct. Use lrm(Y ~ pol(x, 2))
Frank
------------------------------------------
--
Joris Meys
Statistical Consultant
Ghent University
Faculty of Bioscience Engineering
Department of Applied mathematics, biometrics and process control
Coupure Links 653
B-9000 Gent
--
Frank E Harrell Jr Professor and Chairman School of Medicine
Department of Biostatistics Vanderbilt University
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