[R] Negative Binomial Regression - glm.nb

[Martin Spindler]

Dear all,

I would like to ask, if there is a way to make the variance / dispersion parameter $\theta$ (referring to MASS, 4th edition, p. 206) in the function glm.nb dependent on the data, e.g. $1/ \theta = exp(x \beta)$ and to estimate the parameter vector $\beta$ additionally.

If this is not possible with glm.nb, is there another function / package which might do that?

Thank you very much for your answer in advance!

Best,

Martin