5.3 - Money Growth & Inflation
Inflation as a monetary phenomenon
Inflation refers to a sustained increase in the general price level of goods and services in an economy over time. This rise in prices reduces the purchasing power of money, meaning each unit of currency buys fewer goods and services. Deflation, in contrast, is a sustained decrease in the general price level.
Inflation and deflation are closely tied to changes in the money supply, which is the total amount of money available in an economy, including currency and deposits. When the money supply increases too rapidly over a long period, it leads to inflation because more money chases the same amount of goods and services, driving up prices. Conversely, a rapid decrease in the money supply can cause deflation, as less money in circulation reduces demand and lowers prices.
This relationship shows that inflation is fundamentally a monetary phenomenon, resulting from imbalances between the growth of money and the economy's ability to produce goods and services. For example, if the money supply grows faster than real output, prices will rise to restore balance.
The quantity theory of money
The quantity theory of money is an economic model that explains the relationship between the money supply and the price level in the long run. It assumes that changes in the money supply directly affect prices when the economy is at full employment, which is the level of output where all available resources are used efficiently, with no cyclical unemployment.
Key components of the quantity theory
According to this theory, the money supply influences prices through a specific equation, but it does not affect real output in the long run. Real output refers to the total value of goods and services produced, adjusted for price changes.
Formula for the quantity theory of money:
Where:
- M = Money supply (total amount of money in the economy)
- V = Velocity of money (average number of times a unit of money is spent on final goods and services per year)
- P = Price level (average level of prices in the economy)
- Q = Real output (quantity of goods and services produced)
This equation shows that the product of money supply and velocity equals the product of price level and real output. If velocity and real output remain constant, an increase in money supply leads to a proportional increase in the price level, causing inflation.
Long-run implications of money supply changes
In the long run, changes in the money supply have specific effects on the economy, particularly when it operates at full employment. At this point, the economy cannot produce more real output without causing inflation, so extra money primarily affects prices.
Effects on real output and prices
When the economy is at full employment, increasing the money supply does not boost real output in the long run. Instead, it leads to higher prices as the extra money competes for the same goods and services.
Key relationships:
- The growth rate of the money supply determines the inflation rate, which is the percentage increase in the price level over time.
- For instance, if the money supply grows by 5% annually while real output grows by 2%, the inflation rate would be approximately 3% according to the quantity theory.
- Decreasing the money supply at a rapid rate can lead to deflation, but it also does not change real output in the long run; it mainly lowers the price level.
These implications highlight that monetary policy, which involves managing the money supply, focuses on controlling inflation rather than permanently increasing output.
Calculating with the quantity theory of money
The quantity theory allows for calculations of key economic variables by rearranging its formula. This is useful for determining outcomes like the required money supply or expected price level given certain conditions.
You can solve for any variable if the others are known. For example, to find the price level, rearrange to P = (M × V) / Q.
Worked example - Calculating the price level using the quantity theory
An economy has a money supply of $2,000 billion, velocity of money of 4, and real output of $2,500 billion. Calculate the price level.
Step 1: Identify the values
- Money supply (M) = $2,000 billion
- Velocity (V) = 4
- Real output (Q) = $2,500 billion
Step 2: Apply the quantity theory formula
Step 3: Substitute and calculate
Step 4: Interpretation
The price level is 3.2, meaning the average price of goods and services is 3.2 times higher than in a base period. This indicates potential inflation if the money supply grew rapidly to reach this point.
Worked example - Calculating the money supply using the quantity theory
Suppose an economy aims for a price level of 2.5, with velocity of money at 5 and real output at $1,600 billion. Calculate the required money supply.
Step 1: Identify the values
- Price level (P) = 2.5
- Velocity (V) = 5
- Real output (Q) = $1,600 billion
Step 2: Rearrange and apply the formula
Step 3: Substitute and calculate
Step 4: Interpretation
The money supply needs to be $800 billion to achieve the target price level, assuming velocity and real output remain constant. A higher money supply could lead to inflation.