In recent years there has been considerable debate in the literature on economic stabilization and in policy discussions regarding the ability of monetary authorities to achieve a desired growth of nominal income by controlling the growth of the money stock. This debate concerns the predictability of the response of the growth of income to a change in the growth of money. A frequently cited piece of evidence in support of the view that this response is not very predictable has been observed movements in the income velocity of money—nominal income divided by the money stock.