Are the "ASEAN Plus Three" Countries Coming Closer to an OCA?

After the global financial crisis, it has become more recognized that the policy dialogues among both emerging and advanced economies on the exchange rate is necessary to prevent competitive devaluation. In this context, East Asian countries should also choose an adequate exchange rate system. However, there still exists a variety of exchange rate regimes in this area, which might suggest a possibility of coordination failure. To avoid this, the establishment of stable exchange rate linkages and the enhancement of monetary policy credibility in East Asia are needed. These discussions on common regional exchange rate policy are often related to the "Optimum Currency Area (OCA) theory" because stabilized exchange rates in the global economies are only assured by a "one size fits all" monetary policy in the end. Hence, the main purpose of this paper is to investigate whether East Asian countries—ASEAN5, China, Korea, and Japan—have developed into matching an OCA in recent years or not. While developing the earlier generalized purchasing power parity (G-PPP) model into an up-to-date non-linear econometric model and considering the adoption of the Asian monetary unit (AMU) into this area, this paper could have positive empirical results which suggest for forming a common currency in East Asia.