Probit model Hessian matrix of the log-likelihood
| Parameters: | params : array-like
|
|---|---|
| Returns: | The Hessian evaluated at `params` : |
Notes

where
.. math:: lambda_{i}=frac{q_{i}phileft(q_{i}x_{i}^{prime}betaright)}{Phileft(q_{i}x_{i}^{prime}betaright)}
and 