statsmodels.genmod.families.links.Power.inverse_deriv2¶ Power.inverse_deriv2(z)[source]¶ Second derivative of the inverse of the power transform Parameters:¶ z : array_like¶z is usually the linear predictor for a GLM or GEE model. Returns:¶ g^(-1)’(z) (ndarray) – The value of the derivative of the inverse of the power transform function