# Concepts

## Adjustment for seasonal variation

Seasonal adjustment means the estimation of seasonal variation and the elimination of its impact from a time series. The obtained result is a seasonally adjusted time series. The trend of a time series is obtained when both seasonal variation and irregular random variation are eliminated from a time series. Trading or working day adjusted series are in turn obtained when the factors caused by the variation in the number of trading days or weekdays is eliminated from the observation of the original time series. The Tramo/Seats method is used for the seasonal adjustment of time series at Statistics Finland. In the Tramo/Seats method, preadjustment is based on a regression model (which allows for outlying observations, public holidays and the weekday structure) and the seasonal adjustment proper on an ARIMA model constructed for the time series.

#### Topic

- Menetelmäkäsitteet

#### Validity of the definition

- Valid until (31 December 2078)

#### Source organisation

- Tilastokeskus

#### Related concepts

Seasonal adjustment means the estimation of seasonal variation and the elimination of its impact from a time series. The obtained result is a seasonally adjusted time series. The trend of a time series is obtained when both seasonal variation and irregular random variation are eliminated from a time series. Trading or working day adjusted series are in turn obtained when the factors caused by the variation in the number of trading days or weekdays is eliminated from the observation of the original time series. The Tramo/Seats method is used for the seasonal adjustment of time series at Statistics Finland. In the Tramo/Seats method, preadjustment is based on a regression model (which allows for outlying observations, public holidays and the weekday structure) and the seasonal adjustment proper on an ARIMA model constructed for the time series.

#### Statistics using the definition

- Index of turnover in industry
- New orders in manufacturing
- Turnover estimate of large enterprises
- Index of turnover of construction
- Turnover of service industries
- Quarterly national accounts
- Wage and salary indices
- Flash estimate of GDP on quarter
- Trend Indicator of Output
- Turnover of trade
- General government revenue and expenditure by quarter

#### Validity of the definition

- Valid until (31 December 2078)

#### Source organisation

- Tilastokeskus

Jaa