@cache_readonly
    def bse(self):
        params = self.params
        hess = self.model.hessian(params)
        if len(params) == 1:  # can't take an inverse, ensure 1d
            return np.sqrt(-1./hess[0])
        return np.sqrt(np.diag(-inv(hess)))
dataset/ETHPy150Open statsmodels/statsmodels/statsmodels/tsa/arima_model.py/ARMAResults.bse/original