Each year, during the second estimate of first-quarter GDP, seasonal adjustment is fine-tuned again while outliers are once again identified and established. However, this was not the case in the past two years, because the entire period from Q1 2020 to Q1 2022 was treated as an outlier due to the exceptional economic circumstances. This was in line with Eurostat's recommendations. Eurostat has meanwhile given the Member States the liberty to make their own adjustments.
With effect from the second estimate of Q1 2022, the full pandemic period is no longer treated as an outlier during fine-tuning of the seasonal adjustment; therefore, the seasonal adjustment factors have been redefined for the whole series including the period Q1 2020 Q1 – Q1 2022 while the outliers have been re-established. This means CBS has switched back to the working method of the pre-pandemic period, which takes into account changes in quarterly patterns.
As a result of reverting to the original working method, some of the adjustments in the quarterly series are larger than usual, compared to the previous publication in May 2022. This is particularly the case for industries with little or no impact from the coronavirus pandemic. At GDP level, adjustments due to reverting to the original seasonal adjustment method have remained limited. In addition to the adjustments as a result of this reversion, of course there have also been adjustments due to the use of new source information, as is the case with each new estimate.