The Optimum Quantity of Money in a Stochastic Economy: A Comment
指出Taub（1989）关于通胀是最优政策的结论源于一阶条件计算错误；当收入受总体冲击且驱动过程为AR(1)时，通缩总是最优政策，且通缩率超过时间偏好率。
In a 1989 paper, B. Taub showed, contrary to T. Bewley's conjecture, that when income is subject to an aggregate shock, inflation may be the optimal policy. This paper shows that the inflation result is due to an algebraic mistake in the calculation of the first-order condition. When income is subject to an aggregate shock, deflation is always the optimal policy if the driving process has an AR(1) representation. Moreover, for a stationary AR(1) process, the rate of deflation exceeds the rate of time preference, as Bewley conjectured. Copyright 1992 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.