sorry to bump in late, but I am doing similar things now and was browsing.
IMHO anova is not appropriate here. it applies when the richer model has p
more variables than the simpler model. this is not the case here. the
competing models use different variables.
you are left with IC.
by
On Thu, 2 Sep 2010, stephenb wrote:
sorry to bump in late, but I am doing similar things now and was browsing.
IMHO anova is not appropriate here. it applies when the richer model has p
more variables than the simpler model. this is not the case here. the
competing models use different
Totally agreed.
I made a mistake in calling the categorization a GAM. If we apply a step
function to the continuous age we get a limited range ordinal variable.
Categorizing is creating several binary variables from the continuous (with
treatment contrasts).
Stephen B
-Original
?anova.coxph
will tell you that there's an additional parameter, test, taking
values F, Cp, or Chisq which instructs the anova method to
perform the stated test comparing the two models and spit out a p-
value (for F and Chisq at least).
example(anova.chisq) provides some examples.
Cheers,
Windows XP
R 2.8.1
I am trying to use anova(fitCont,fitCat) to compare two Cox models (coxph) one
in which age is entered as a continuous variable, and a second where age is
entered as a three-level factor (young, middle, old). The Analysis of Deviance
Table produced by anova does not give a p
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