7.2.3.3.7.3. statsmodels.genmod.families.family.Poisson.loglike¶

Poisson.loglike(endog, mu, scale=1.0)[source]¶

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