We argue that if currency union member states have different potential output per capita, output growth rates, or trade balances, the common monetary policy may not be optimal for all of them. Euro area imbalances for potential output and for trade balances are quite large, while output growth...

We develop multivariate measures of synchronicity and co-movement of business cycles. In addition to synchronicity, the co-movement measure takes differences between cycle amplitudes into account that have been overlooked in most previous studies. We apply the new measures to the euro area....