5. Conclusions
Gamber and Liebner (2017) raise important issues concerning the interpretation of empirical results, particularly when employing impulse indicator saturation. In the discussion above, the analysis of alternative model specifications and the calculation of empirical power functions highlight consequences for IIS when the null hypothesis is incorrect. Specifically, IIS has power to detect many empirical features, including heteroscedasticity, structural breaks, outliers, and omitted variables. As a practical implication, the evidence in Ericsson (2017) and Gamber and Liebner (2017) supports the interpretation that U.S. government agencies’ forecasts of U.S. gross federal debt have time-varying biases.