Concurrent adjustment

According to the ESS Guidelines on Seasonal Adjustment (2015), concurrent adjustment means that every time a new observation is available, the model, filters, outliers, regression variables and transformation type are re-identified and the corresponding coefficients and factors are re-estimated. This means that the previous specification and results are wiped off and that the adjustment process is started again from scratch.

The example below shows the initial model (left) and the results of the refreshment procedure with the Concurrent adjustment option (right). The transformation type has changed from none to log and the ARIMA orders have been re-identified (from (0,1,1)(1,1,0) to (1,1,0)(0,1,1)). The regression model has also changed: trading days and leap year are considered irrelevant for this series, and the number of outliers has drastically reduced.

The Concurrent adjustment revision policy results