[R] nesting in CoxPH with survival package
kanweile at gmail.com
Sat Jan 12 02:35:19 CET 2013
I am trying to understand how to specify nested factors when using
coxph(), and if it is appropriate to nest these factors in my
In the simplest form, I am testing two different temperatures, with
each temperature being performed twice in different experimental
periods (e.g. Temp5 performed in Period A and C, Temp4 performed in
Period B and D)
I am trying to see if survival time is affected by the treatment
temperature. To do this I am using temperature and experimental
period nested within temperature as factors.
In coxph(LOE.stable.5days ~ Temp + Temp/Period, :
X matrix deemed to be singular; variable 2 5 6 7
1. Is this an appropriate way of nesting?
2. Can this error message be ignored?
Any help would be much appreciated, thank you in advance.
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