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Seasonal adjustment models have been revised

The seasonal adjustment models used have been revised in connection with the calculation of the indices of turnover for September. The revisions influence the seasonally adjusted and trend series, but not the original or working-day adjusted time series. The change percentages calculated from the original series have thus become only slightly revised, and this is due to new data having become available.

Statistics Finland has introduced level shifts in the seasonal adjustment models of certain industries. This has a significant impact on the development of the seasonally adjusted and trend time series in 2008 and 2009.

Without the level shifts the downturn would not show so steep at the turn of 2008-2009. For more detailed information about the revised treatment of seasonal adjustment, see http://tilastokeskus.fi/ajk/tiedotteet/2009/tiedote_019_2009-12-08_en.html. Seasonally adjusted and trend time series always become revised against new observations irrespective of whether the original time series becomes revised or not. Especially in exceptional economic situations as at present seasonally adjusted data contain more uncertainties than usual.

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Last updated 15.12.2009