These findings have important implications for monetary cooperation in East Asia. Bayoumi
and Mauro (1999) have calculated an Optimal Currency Area (OCA) index for East Asia based
on historical data of debt patterns and nature of disturbances and concluded that ‘‘on economic
criteria, ASEAN appears less suited for a regional currency arrangement than Europe before the
Maastricht Treaty was signed, although the difference was not large’’ (see page 1). The findings
of this paper that trade integration is leading to synchronization of business cycles, together with
the findings of Frankel and Rose (1998) that the level of trade integration increases significantly
after the formation of a currency union, suggest that although ex ante East Asia may not be a good
candidate for a currency union, ex post (based on endogenous factors) it could be. The latter
factors are important because trade expansion due to the formation of a currency union could lead
to greater synchronization of business cycles, which in turn reduces the costs of a union by
increasing the incidence of symmetric shocks.