2.1. Theoretical Foundations
Economic agents usually keep money for two purposes: to store value and to conduct transactions. Generally, economic instability affects the amount of money these brokers are willing to hold. For example, an increase in interest rate volatility and an increase in the risk of inflation make all nominal assets risky. This is because the value of these types of goods and services is less predictable. Thus, in an unstable inflationary environment, economic actors can convert their nominal assets, including money, into other assets such as gold (Atta Mensa, 2004).
The money demand function plays an important role in understanding the transmission of changes in the money supply and other variables, such as interest rates, to the economy (Azizi et al, 2024). Since the 1930s, economists have put forward theories in order to determine the factors that hold money.
Fischer(1911) and Pigo (1917) showed that there is a direct and proportional relationship between the amount of money and the level of price in the form of classical equilibrium. These two emphasize the role of money as a medium of exchange in transactions. In the theory of quantity of money, the demand for money is not precisely discussed, but it is the trading speed of the circulation of money that is emphasized (Zara-Nejad et al, 2006).
In the Fisher exchange relationship, the amount of money in circulation for a given period is related to the level of full employment and the exchange price of
for a given period through the speed of the trading circulation of
. Fisher assumes that in the short term, the speed of money circulation is constant and that the amount of money is determined independently of the trading volume. On the other hand, in the framework of equilibrium based on classical full employment, it is assumed that there is a constant rate between the level of transactions and production: Therefore,we have:
In the Cambridge approach, Marshall(1923) stated that the level of holding money is related to the number of transactions. When people's wealth increases, they hold more financial assets, one of which is money (Kuan et al, 2012).
In this regard, k represents the tendency of people to keep a portion of their income in the form of money, which is the opposite of the speed at which money circulates, except that here it refers to the speed at which people convert their money into commodities (Bedrom, 1999).
Keynes argues that people hold money because of three motives: transactional, precautionary, and speculative. Following Fisher and Cambridge economists, Keynes (1936) argues that the transactional demand for money is a constant function of income. On the other hand, in addition to holding money for their current transactions, people also hold some money in order to meet their needs and expected payments in the future. which is known as precautionary motivation (Khalili Iraqi, 2005).
The difference between Keynes's view of money and other views on the speculative demand for money is that it shows the relationship between the demand for money and the interest rate. He states that people hold a combination of money and bonds that have yields. In such a way that the expectation of an increase in the interest rate in the future will increase the speculative demand for money, and conversely, the liquidity preference function of Keynes is:
In this function, the real demand for money is a function of income and interest rate
Baumol (1952) and Tobin (1956) sought to introduce a theory in which money is essentially an entity that is held for a transactional purpose. Although financial assets other than money have a higher return than money, the transaction cost of converting financial assets into money when needed justifies holding money.
The household asset portfolio consists of two asset groups: assets that have returns and generate income, and money that covers the gap between payments and receipts. Transaction costs are incurred when non-monetary assets are sold to finance the transaction. In this case, holding more money minimizes the transaction cost and, on the other hand, causes a loss of interest income. The optimal point, which can yield the minimum trading cost and the maximum interest for individuals, is determined based on the following relationship (Fallahi, 2005):
،a، y، and r represent optimal demand for money, transaction costs, real income, and interest rates, respectively (Dehmardeh et al, 2009).
Friedman(1956) believes that people keep money in order to buy the services and goods they need. He states that because money is a durable commodity with invisible services, it enters into the functions of desirability and production. On the other hand, money is compared to other assets such as bonds, stocks, and durable goods. In such a way that if the amount of money held increases, the ultimate desirability of monetary services decreases. In summary, Friedman emphasizes two points: first, he does not consider the expected rate of return of money to be fixed, and assuming that the demand for money also depends on the motivation to hold other assets, he states that the demand for money does not show sensitivity to changes in the interest rate. So if the interest rate increases, because the expected rate of return of money held in the form of bank deposits will also increase, it will not have much effect on reducing the incentive to hold money. Therefore, changes in interest rates do not have a significant effect on the demand for money, and it is only the permanent income of individuals that affects their demand for money (Farzin et al, 2012).
Secondly, Friedman, unlike Keynes, believes that the demand for money function is stable, which means that the amount of money demanded can be predicted by the demand for money function, and on the other hand, the speed of money circulation is completely predictable due to the insensitivity of the demand for money to the interest rate (Khalili et al, 2013).
Nowadays, the demand for money is studied over both short- and long-term periods. Obviously, an increase in the amount of money demand in the long run can only occur as a result of an increase in the amount of production in a country. Therefore, if the amount of domestic production increases in society and there is a demand for the purchase of these products, then the central bank will face an increase in the demand for money and will issue money, which will result in price stabilization and economic growth.
Otherwise, and with the continuation of the issuance of money regardless of the country's production trend, it will have no effects other than inflationary pressure. However, in long-term studies of money demand, the increase in the amount of domestic production, which is sometimes interpreted as economic dynamism, is measured using the index of industrial production, or GDP (Snowden, 2010).
2.2. Litrature Review
In this section, the empirical studies conducted in the field of estimating the money demand function and the factors affecting it over different time periods have been examined.
Kuan Payne and Jones(2012) investigated the stability of the short-run money demand function in the United States for the period 1959–1981. The results of the fitted regression equation for the period could not confirm the test of the transfer hypothesis in the money demand function in the United States in 1971, and the results indicated the stability of the money demand function for the period under consideration.
Prakash et al.(2012) investigated the money demand function based on the Naranslog function model in Malawi and its policy strategies. For this purpose, it was tried to estimate the money demand function for the period 1985–2010 using annual data and econometric methods. During the period under study, several structural failures occurred in the economy of this country. It showed the existence of a long-run relationship between real money balances, prices, income, the exchange rate, Treasury bonds, and financial innovations. However, all variables have a significant impact on the demand for money in the short and long run. Therefore, policy-making should be done in order to increase financial innovation, improve economic activities, and achieve higher returns.
Lee and Chang(2012), investigated the money demand function in China based on an explanatory model with bounded distributional lags. For this purpose, they used the data between 1976 and 2006 and the mentioned model. Their results showed that there is a long-run relationship between the limited definition of money, real income, and the nominal interest rate. It was equal to 0.915 and -0.0002 for the Chinese economy, respectively.
Prakash and Manoj, (2012) investigated whether there is a stable, long-term relationship between money demand in India. For this purpose, they used the Georg-Hansen model for the period 1953–2008. The results of the co-combination test showed that there is a long-run relationship between money demand, real GDP, and the nominal interest rate, despite the structural failure in 1965. The results also showed a downward movement of the demand function by 0.33% in 1965.
Kumar et al. (2010) investigated the level of stability of money demand in Nigeria during the period 1960-2008 using error correction models and stability test of the money demand function of this country. The results of their research showed that the demand for money is efficiently stable, so the policymakers of this country can use the money supply as a policy tool.
Bafandeh Imandoost and Ghasemi (2011) investigated the factors affecting Iran's money demand under uncertain conditions for the period between 1975 and 2006. In this paper, they used the Bayesian model averaging method to consider the uncertainty assumption of the model due to its appropriate features. Gross Domestic Product (GDP), Price Index of Goods and Services, Official Exchange Rate, Budget Deficit to GDP, Dependent Variable with Interruption, and Price Index of Goods and Services with Interruption.
Dehmardeh and Izadi (2009) investigated the money demand function in Iran. The purpose of this study was to estimate the money demand function in Iran for the period 1971–2008 using the ARDL method and to investigate the relationships between independent and dependent variables. The results showed that there is a long-run equilibrium relationship between the variables in this estimate. The coefficient of the GDP variable indicates a positive and significant effect of this variable on the money demand function. On the other hand, the relationship between free market exchange rate variables and inflation on the money demand function was negative and indicated an inverse and significant effect between these variables and the dependent variable.
Khalili et al, (2013) studied the demand for money in Iran using error correction and collage models during the years 1971–2011. Based on the estimated relationship and the income elasticity coefficient of the demand for money with a 1% increase in GDP, the demand for cash balance increases by 1.82%. The estimated coefficient for the exchange rate (-0.34) indicates the substitution of domestic and foreign currencies. The long-term interest rate coefficient is significant and indicates the negative interest elasticity of money demand in Iran. Also, the results of the stability test showed that the demand for money during this period is stable.