Is the stationarity of the yen real exchange rates a puzzle ?

This paper attempts to shed light on the puzzling finding that the results of applying the conventional or nonlinear unit root tests to the yen real exchange rates (RERs) in some recent studies appear to be rather sensitive to whether or not including the data of recent decade in the studies. It is found that this sensitivity of the test results may come from the failure to take into account the large rise and fall in the yen RERs. Using the newly developed unit root tests which account for the presence of multiple smooth temporary breaks in the RERs, the results clearly show that the yen RERs in the post-Bretton Woods period can be characterized as being linear or nonlinear stationary around infrequent smooth temporary mean changes, supporting the validity of PPP.