Velocity of Money
The velocity of money is the rate at which money circulates in the economy, measured as the ratio of nominal income to the money supply. It indicates how many times, on average, a unit of money is used in transactions in a given period.
Definition and Measurement
Velocity is defined by the equation of exchange, in which the money supply multiplied by velocity equals the price level multiplied by real output. Rearranged, velocity equals nominal output divided by the money supply. Different measures of the money supply yield different velocities.
The income velocity, based on nominal income, is the most commonly used measure. The transactions velocity, based on the total value of transactions, is larger, since it includes intermediate and financial transactions as well as final purchases. The choice of measure depends on the purpose of the analysis.
Determinants
Velocity depends on payment practices, on the availability of substitutes for money, and on interest rates. Improvements in payment technology, including electronic payments and credit cards, increase velocity by reducing the need to hold money. Higher interest rates increase velocity by raising the opportunity cost of holding money.
Financial innovation and changes in the structure of the financial system alter velocity over time. The development of interest-bearing deposits, of money market funds, and of other instruments changes the demand for different measures of money and thus their velocities.
Implications for Monetary Policy
The quantity theory of money relates the money supply to the price level through velocity. If velocity is stable, changes in the money supply translate into proportional changes in prices, and monetary targeting is feasible. If velocity is unstable, the relationship breaks down, and the control of the money supply is a less reliable instrument.
The instability of velocity, particularly in recent decades, contributed to the decline of monetary targeting in favour of inflation targeting. Central banks now rely primarily on interest rates and on forecasts of inflation rather than on the control of monetary aggregates.
Empirical Behaviour
Velocity has exhibited different patterns over time. In some periods it has been stable and predictable, supporting the use of monetary aggregates as indicators. In other periods, including recent decades, it has been volatile and has trended in different directions, complicating the interpretation of monetary data.
The behaviour of velocity reflects changes in the demand for money and in the financial system. Analysing velocity, and understanding the factors that drive it, is important for interpreting monetary conditions and for assessing the information content of monetary aggregates.
The Equation of Exchange
The equation of exchange, in which the money supply multiplied by velocity equals the price level multiplied by real output, is an identity that holds by definition. Its usefulness depends on the behaviour of its components and on the stability of the relationships among them.
The equation can be interpreted in different ways. As an identity, it defines velocity given the other variables. As a theory, the quantity theory, it assumes that velocity and output are determined independently of the money supply, so that changes in money translate into changes in prices.
Stability of Velocity
The stability of velocity is crucial for the usefulness of monetary aggregates as policy indicators. Where velocity is stable and predictable, changes in the money supply give reliable information about future nominal income. Where velocity is unstable, the information content is reduced.
The evidence suggests that velocity has been unstable, particularly in recent decades, reflecting financial innovation, changes in payment technology, and shifts in the demand for money. This instability contributed to the decline of monetary targeting and to the adoption of other frameworks.
Financial Innovation and Velocity
Financial innovation affects velocity by changing the demand for money and the availability of substitutes. The development of interest-bearing deposits, of money market funds, and of electronic payments has altered the ways in which money is held and used, affecting the velocity of different measures of money.
The effects of innovation on velocity are difficult to predict, since they depend on the nature of the innovation and on the response of households and firms. The analysis of these effects informs the interpretation of monetary data and the design of monetary policy frameworks.
Velocity in Different Economies
Velocity varies across economies, reflecting differences in payment systems, in financial structure, and in the demand for money. Economies with more developed financial systems and more efficient payment technologies tend to have higher velocity, since less money is held relative to transactions.
The comparison of velocity across economies informs the analysis of the demand for money and of the effects of financial development. It also informs the design of monetary policy in economies at different stages of development, where the behaviour of velocity may differ from that in advanced economies.