def _ss_reg(self):
        """Sum of squares of the regression."""
        return np.sum(
            np.square(self._predicted - np.expand_dims(self._ybar, axis=1)),
            axis=1,
        )
def _ss_reg ( self ) : return np . sum ( np . square ( self . _predicted - np . expand_dims ( self . _ybar , axis = 1 ) ) , axis = 1 , )
Sum of squares of the regression.