Doing this well requires a deep knowledge of the data mixed with a goodly dose of economic theory and economic judgment. Members of the Board staff continuously analyze the arriving data to learn what they can about the level and composition of economic activity, inflation, and other key aggregates.
The ECB adopted a more active control of balance sheet developments only at a much later stage, in the course of last year, ultimately leading to the adoption of the expanded asset purchase programme (APP). Through the APP, via its reliance on outright purchases, the ECB regained a more direct control over the size of the balance sheet.