This ECB working paper is worth going through. The potential output calculation is very important for policy makers, because deviations from the economy’s potential output tend to form a large part of the evaluation of macroeconomic performance used by the European Commission and others. Two recent Central Bank working papers discuss the impact on the Irish economy of these measure. See here and here. The estimates have been, shall we say, fairly far off the mark. The chart below shows this. Understanding the potential output calculation is therefore really important when we talk about policy responses to changes in fiscal policy, especially at the EU level.