I don't know if I need to get rid of some data, or what is going on here. Models 1 and 2 work perfectly fine. Model 3 won't run.
model1 <- clogit(Used ~ Slope + strata(OBJECTID), data=old)
model2 <- clogit(Used ~ Aspect + strata(OBJECTID), data=old)
model3 <- clogit(Used ~ Slope + Aspect + strata(OBJECTID), data=old)
Model 3 gives the following error:
> Error in fitter(X, Y, strats, offset, init, control, weights =
> weights, : NA/NaN/Inf in foreign function call (arg 5)
It additionaly gives warnings of:
> In fitter(X, Y, strats, offset, init, control, weights = weights, :
> Ran out of iterations and did not converge
I am less concerned about the warnings as other models also give this, but actually have outputs.
I can post the data if I need to, or if you have an idea that can point me in the right direction, that would be awesome.
-dan
****** Additional Info *******
RPackages: survival
> o.s.model <- clogit(Used ~ Slope + strata(OBJECTID), data=old)
> o.a.model <- clogit(Used ~ Aspect + strata(OBJECTID), data=old)
> o.sa.model <- clogit(Used ~ Slope + Aspect + strata(OBJECTID), data=old)
Error in fitter(X, Y, strats, offset, init, control, weights = weights, :
NA/NaN/Inf in foreign function call (arg 5)
In addition: Warning message:
In fitter(X, Y, strats, offset, init, control, weights = weights, :
Ran out of iterations and did not converge
>
Both Slope and Aspect are numberical.
dataset at: https://drive.google.com/file/d/1AXKMJnDs_JYZmy_gB3IaMXHL34_ejxz3/view?usp=sharing
This could be due to ties in the dataset. Try fitting the model with either the efron or breslow approximation (method='efron'). Solved the issue for me...
see also here: https://stats.stackexchange.com/questions/109222/conditional-logistic-regression-model-does-not-converge-but-logistic-regression
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