statsmodels.genmod.families.varfuncs.NegativeBinomial¶
-
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.
- alpha
Notes
Formulas :
V(mu) = mu + alpha*mu**2
Alias 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.