This comment will explain the differences and respecify some of the equations to dispel any misconceptions in Humpage's earlier article of the same title.

An analysis of U.S. foreign exchange-market intervention and its effect on dollar depreciation, finding there is no systematic relationship between intervention and daily exchange-rate movements.

An introduction to a new exchange-rate index to measure the foreign-exchange value of the dollar. The authors develop a model of U.S. merchandise trade, featuring the new index.

Since the early seventies, the U.S. dollar has been allowed to float freely, and its exchange rates have become extremely volatile and difficult to explain, let alone to predict. The dollar's erratic behavior has stimulated a lively debate in academic and policy circles over what the...