[R] [EXT] Theta from negative binomial regression and power_NegativeBinomiial from PASSED

Andrew Robinson @pro @end|ng |rom un|me|b@edu@@u
Fri Sep 15 04:05:33 CEST 2023

Hi John,

the negative binomial is a tricky one - there are several different parameterisations and therefore different interpretations of the parameters.  Joseph Hilbe wrote a whole book on it that might be wroth checking.



Andrew Robinson
Chief Executive Officer, CEBRA and Professor of Biosecurity,
School/s of BioSciences and Mathematics & Statistics
University of Melbourne, VIC 3010 Australia
Tel: (+61) 0403 138 955
Email: apro using unimelb.edu.au
Website: https://researchers.ms.unimelb.edu.au/~apro@unimelb/

I acknowledge the Traditional Owners of the land I inhabit, and pay my respects to their Elders.
On 15 Sep 2023 at 11:52 AM +1000, Sorkin, John <jsorkin using som.umaryland.edu>, wrote:
External email: Please exercise caution


I want to use the power_NetativeBinomial function from the PASSED library. The function requires a value for a parameter theta. The meaning of theta is not given in the documentation (at least I can�t find it) of the function. Further the descriptions of the negative binomial distribution that I am familiar with do not mention theta as being a parameter of the distribution. I noticed that when one runs the glm.nb function to perform a negative binomial regression one obtains a value for theta. This leads to two questions

1. Is the theta required by the power_NetativeBinomial function the theta that is produced by the glm.nb function
2. What is theta, and how does it relate to the parameters of the negative binomial distribution?

Thank you,

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