Logit model Hessian matrix of the log-likelihood
| Parameters: | params : array-like
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|---|---|
| Returns: | hess : ndarray, (k_vars, k_vars)
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Notes
\frac{\partial^{2}\ln L}{\partial\beta\partial\beta^{\prime}}=-\sum_{i}\Lambda_{i}\left(1-\Lambda_{i}\right)x_{i}x_{i}^{\prime}