Data refer to end-of-month outstanding stocks as consolidated at the euro area level, and the associated flows, indeces of adjusted stocks and growth rates.
Seasonal adjustment is the process of estimating and removing seasonal effects from a time series. The seasonal adjustment procedures used by the ECB also cater for the trading-day adjustment.
The approach used to seasonally adjust the euro area monetary aggregates and counterparts relies on a multiplicative decomposition using the X-12-ARIMA method. For internal purposes, the model-based approach of TRAMO-SEATS is also used. As the series are collected as end-of-month stocks, trading-day adjustment is performed where applicable. Outliers are taken into consideration in order to minimise distortions to the estimated seasonal and trading-day components.
To ensure the additivity of the seasonally adjusted components to the seasonally adjusted aggregates, some of the seasonally adjusted series, in particular M3, are derived indirectly. From a numerical point of view, the difference between direct and indirect estimates of euro area monetary aggregates is regularly monitored and has proved to be generally negligible.
Forecast seasonal factors are used. In addition, seasonal factors are revised whenever required, for example, in the case of large data revisions or the statistical inadequacy of the models used when new data are incorporated. For this purpose, a concurrent adjustment is run on a monthly basis in order to assess the validity of the seasonal factors in use.
The specific procedures followed by the ECB in the seasonal adjustment of time series are reviewed in detail in the Manual on MFI balance sheet statistics [2.51 MB] .