Formula parsing and updating
Charles C. Berry <cberry at tajo.ucsd.edu> [Fri, Dec 05, 2008 at 01:21:41AM CET]:
On Thu, 4 Dec 2008, Johannes Huesing wrote:
somemod$formula
Surv(lebzeit, tot == 1) ~ sex + (alter >= 65) + diff3k + zelltyp_k_c + q_nuc_3k + kar_k80_g80 + stadium
You need to give us something to reproduce. I get an error when I try
example(coxph) test1$quant <- rnorm(length(test1$sex)) fit <- coxph( Surv(time, status) ~ x + (quant>0) + strata(sex), test1)
Error in model.matrix.default(newTerms, m) : model frame and formula mismatch in model.matrix()
Odd, since I had no problem entering the formula in this naive way.
When I protect with I(quant>0), I have no problems obtaining 'fit' nor update()ing it:
I was unaware of I(), and this did the trick for me. Thank you!
Johannes H?sing There is something fascinating about science.
One gets such wholesale returns of conjecture
mailto:johannes at huesing.name from such a trifling investment of fact.
http://derwisch.wikidot.com (Mark Twain, "Life on the Mississippi")