The Holt-Winters Filter and the One-Sided Hp Filter : A Close Correspondence

We show that the trend of the one-sided HP filter can be asymptotically approximated by the Holt-Winters (HW) filter. The later is an elegant, moving average representation and facilitates the computation of trends tremendously. We confirm the accuracy of this approximation empirically by comparing the one-sided HP filter with the HW filter for generating credit-to-GDP gaps. We find negligible differences, most of them concentrated at the beginning of the sample