statsmodels.genmod.families.family.Poisson.loglike

Poisson.loglike(endog, mu, scale=1.0)

Loglikelihood function for Poisson exponential family distribution.

Parameters:

endog : array-like

Endogenous response variable

mu : array-like

Fitted mean response variable

scale : float, optional

The default is 1.

Returns:

llf : float

The value of the loglikelihood function evaluated at (endog,mu,scale) as defined below.

Notes

llf = scale * sum(-mu + endog*log(mu) - gammaln(endog+1)) where gammaln is the log gamma function