[R-sig-ME] R Squared for GLMM with gamma distribution

[David Winsemius]

> On Jul 23, 2018, at 12:08 PM, moses selebatso via R-sig-mixed-models <r-sig-mixed-models using r-project.org> wrote:
> 
> Dear R
> I am trying to calculate the coefficient of determination, R2 for gamma distribution data, but I cant find the right r package or script for it. Any ideas?
> Thank you, in advance
> Mos
> 	[[alternative HTML version deleted]]

One clarifying question might be how do you know that the gamma distribution properly describes the errors of your data situation? The fact that a value appears to be "gamma" when viewed as a single value does not mean that the errors around a well-constructed model will have gamma-distributed errors.

Another clarifying question: What do you expect for a "coefficient of determination" if you were performing some sort of regression that was suited for data that remained gamma-error distributed? You might look at the multiple "R^2" variants that exist for models constructed with logistic regression. They all  fail in some manner or another to live up to the expectations generated by the "original" R^2 developed for linear models.

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David Winsemius
Alameda, CA, USA

'Any technology distinguishable from magic is insufficiently advanced.'   -Gehm's Corollary to Clarke's Third Law