Step function

Hi All,

Does the step function work in this model?  I tried to run the
following model but  no result obtained. The computer is hanging and I
killed the job several times. Below is the code.

library(survival)
m.fit=clogit(y~x1+x2+x3+x4, data=ftest)
summary(m.fit)
final<- step(m.fit)

You need to "provide commented, minimal, self-contained, reproducible 
code" such as:

fit <- clogit(I(state=='treated')~.,Puromycin)
step(fit)

which runs just fine.

You have no strata() in your formula. Are you sure you want clogit??

If so, use an idiom like

 	step(fit, scope=list(lower=~strata(stratvar)) )

HTH,

Chuck

Thanks in advance.

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and provide commented, minimal, self-contained, reproducible code.

Charles C. Berry                            (858) 534-2098
                                             Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	            UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901