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

[Andrew Robinson]

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.

Cheers,

Andrew


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

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On 15 Sep 2023 at 11:52 AM +1000, Sorkin, John <jsorkin using som.umaryland.edu>, wrote:
External email: Please exercise caution

Colleagues,

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,
John

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