statsmodels.discrete.discrete_model.Poisson.hessian_factor¶
- Poisson.hessian_factor(params)[source]¶
Poisson model Hessian factor
- Parameters:
- paramsarray_like
The parameters of the model
- Returns:
- hess
ndarray, (nobs,) The Hessian factor, second derivative of loglikelihood function with respect to the linear predictor evaluated at params
- hess
Notes
\[\frac{\partial^{2}\ln L}{\partial\beta\partial\beta^{\prime}}=-\sum_{i=1}^{n}\lambda_{i}\]where the loglinear model is assumed
\[\ln\lambda_{i}=x_{i}\beta\]