statsmodels.genmod.families.varfuncs.NegativeBinomial¶
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class
statsmodels.genmod.families.varfuncs.
NegativeBinomial
(alpha=1.0)[source]¶ Negative binomial variance function
Parameters: alpha : float
The ancillary parameter for the negative binomial variance function. alpha is assumed to be nonstochastic. The default is 1.
Notes
Formulas :
V(mu) = mu + alpha*mu**2Alias for NegativeBinomial: nbinom = NegativeBinomial()
A private method _clean trims the data by machine epsilon so that p is in (0,inf)
Methods
call Returns the negative binomial variance Methods
deriv
(mu)Derivative of the negative binomial variance function.