The adoption of the euro in 1999 by 11 member states of the European Union created a single currency area second in economic size only to the United States. The euro zone's monetary policy is now set by the European Central Bank (ECB) and its Governing Council rather than by individual national...

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....