# Is Hodrick-Prescott filter optimal with irregular component?

I need to extract cyclical component from time series, when doing seasonal adjustment I have the option to remove, apart from seasonal component, the irregular component. Then I'll apply HP to the resulting series, should I leave there or remove the irregular component?

• I thought the irregular component was the noise left in the series after the trend, level and cyclical were removed ? Perhaps the terminology one of us is using is different ? Jun 20 at 16:34
• Jun 23 at 2:09