# One-sided HP filter

**URL:** <https://forum.dynare.org/t/one-sided-hp-filter/3976>\
**Category:** ML/Bayesian estimation\
**Created:** [18 June 2014 12:40 UTC](https://forum.dynare.org/t/one-sided-hp-filter/3976 "2014-06-18T12:40:23Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![jpfeifer](https://forum.dynare.org/user_avatar/forum.dynare.org/jpfeifer/32/5044_2.png) [@jpfeifer](https://forum.dynare.org/u/jpfeifer)\
**Post date:** [18 June 2014 15:45 UTC](https://forum.dynare.org/t/one-sided-hp-filter/3976/4 "2014-06-18T15:45:30Z")

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Because of the Kalman filtering approach, the sample mean of the trend component is always approximately zero (and not exactly zero as for HP-filtering) and becomes closer to zero the longer the data series (asymptotically). I will update the guide accordingly. Thanks for pointing this out.

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