What is seasonal adjustment?
Seasonal adjustment is an important statistical method with three main purposes:
- Aid in short term forecasting
- Allow comparability in the time series from month to month
- Compare movements in different series once individual seasonality has been removed
In practice, seasonal adjustment is a widely applied procedure and there are many different statistical methods to do this. Typically, national statistics institutes will calculate seasonally adjusted estimates on a regular basis and publish these estimates as output for key social and economic indicators.
The links below provide more detail on seasonal adjustment issues faced by international and national statistics institutes:
- Australian Bureau of Statistics: Time series analysis frequently asked questions
- Eurostat: ESS Guidelines on seasonal adjustment
- Office for National Statistics, United Kingdom: Guide to seasonal adjustment
- Statistics Canada: Seasonal adjustment and trend-cycle estimation
- Statistics New Zealand: Seasonal adjustment in Statistics New Zealand
- United States Census Bureau: Frequently asked questions on seasonal adjustment