This paper provides evidence on the reliability of euro area real-time output gap estimates. A genuine real-time data set for the euro area is used, including vintages of several sets of euro area output gap estimates available from 1999 to 2010. It turns out that real-time estimates of the output gap tend to be characterised by a high degree of uncertainty, much higher than that resulting from model and estimation uncertainty only. In particular, the evidence indicates that both the magnitude and the sign of the real-time estimates of the euro area output gap are very uncertain. The uncertainty is mostly due to parameter instability and model uncertainty, while data revisions seem to play a minor role. Some euro area real-time measures, based on multivariate components models and capacity utilisation, are relatively less uncertain, but do not appear to be fully reliable along some dimensions. To benchmark our results, we repeat the analysis for the US over the same sample. It turns out that US real-time estimates tend to be revised to a lesser extent than euro area estimates. However, euro area real-time output gap estimates tend to display a higher correlation with the final estimates and the sign of the level of US real-time estimates tends to be revised more often compared to the corresponding euro area estimates. In addition, the data revision component of the revision error is larger for US estimates than for the euro area. Overall, the unreliability in real-time of the US output gap measures detected in earlier studies is confirmed in the more recent period. (C) 2011 Elsevier B.V. All rights reserved.
