statsmodels.regression.linear_model.OLS.hessian_factor

OLS.hessian_factor(params, scale=None, observed=True)[source]

Calculate the weights for the Hessian.

Parameters

params : ndarray

The parameter at which Hessian is evaluated.

scale : None or float

If scale is None, then the default scale will be calculated. Default scale is defined by self.scaletype and set in fit. If scale is not None, then it is used as a fixed scale.

observed : bool

If True, then the observed Hessian is returned. If false then the expected information matrix is returned.

Returns

ndarray

A 1d weight vector used in the calculation of the Hessian. The hessian is obtained by (exog.T * hessian_factor).dot(exog).