The speed of adjustment or convergence to the steady-state (or equilibrium) value has been an interesting research question. Try to estimate a coefficient, a, of the firstorder auto-regressive model below to estimate a half-life of the real exchange rate of the yen vis--vis the U.S. dollar (q) : qt=aqt1+t where t denotes a white-noise residual series. Then, calculate a half-life for the deviation of the real exchange rate of the yen from its steady-state level. The speed of adjustment or convergence to the steady-state (or equilibrium) value has been an interesting research question. Try to estimate a coefficient, a, of the firstorder auto-regressive model below to estimate a half-life of the real exchange rate of the yen vis--vis the U.S. dollar (q) : qt=aqt1+t where t denotes a white-noise residual series. Then, calculate a half-life for the deviation of the real exchange rate of the yen from its steady-state level