generalized R squared (Naglekerkes R^2)

Question

does anybody know how to compute Naglekerkes generalized R Squared for GLMs using R? And does it makes any sence to use it for count data regression?

References:

generalized R^2

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Answer 1

Try

library(sos)  ## you may have to install.packages("sos") first
findFn("nagelkerke")

This finds functions in various packages: probably most useful are lrm in the rms package (an updated version of the Design package) and NagelkerkeR2 in the fmsb package. Although if by "count data regression" you mean a Poisson rather than a binomial/binary model, lrm won't do it for you. But the other should.

I don't see why it wouldn't apply to count data (Poisson regression) ... although there is always debate about how useful the various analogues of R² are once you get outside the realm of ordinary linear models ...