# Aggregate Demand and Supply

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Aggregate Demand and Supply

Aggregate Demand Macro concept – WHOLE economy Formula:
The sum of all expenditure in the economy over a period of time Macro concept – WHOLE economy Formula: AD = C+I+G+(X-M) C= Consumption Spending I = Investment Spending G = Government Spending (X-M) = difference between spending on imports and receipts from exports (Balance of Payments)

Aggregate Demand Curve
Shows the overall level of spending at different price levels Note – Inflation used for the vertical axis (Assumes Central Banks do not target the money supply but short term interest rates)

Aggregate Demand Curve
Why does it slope down from left to right? Assume Bank of England sets short term interest rates Assume a rise in the price level will be met by a rise in interest rates Any increase in interest rates will raise the cost of borrowing: Consumption spending will fall Investment will fall International competitiveness will decrease – exports fall, imports rise Therefore – a rise in the price level leads to lower levels of aggregate demand

Aggregate Demand Curve
The AD diagram: Inflation on the vertical axis – assume an initial ‘target rate’ of 2.0% (as measured by the HICP or CPI) Real GDP or Real National Income or Real Output on the vertical axis (shown by the initial Y)

Aggregate Demand Curve
The lower level of National Income requires fewer units of labour – unemployment rises to 7% shown by U = 7% At a higher rate of inflation (3.0%) rising interest rates mean that C, I and (X-M) all have negative effects on AD – NY falls to Y2 Inflation This level of output will be associated with a particular level of unemployment which we will call U = 5% At an inflation level of 2%, the AD curve gives a level of output of Y1 3.0% 2.0% AD Y2 Y1 Real National Income U = 7% U = 5%

Shifts in the Aggregate Demand Curve
Any exogenous factor causing C, I or G to rise, or a trade surplus causes a shift to the right in AD This would cause a rise in national income (economic growth) and lead to a fall in unemployment (U = 2%) (and vice versa) Shifts in AD will be caused by changes in factors affecting C, I, G and (X-M) (exogenous factors) e.g. increasing income tax rates affect consumption Inflation 2.0% AD2 AD Y1 Y2 Real National Income U = 5% U = 2%

Consumption Expenditure affected by
Tax rates Incomes – short term and expected income over lifetime Wage increases Credit Interest rates Wealth

Investment Expenditure
Spending on: Machinery Equipment Buildings Infrastructure Influenced by: Expected rates of return Interest rates Expectations of future sales Expectations of future inflation rates

Government Spending Defence Health Social Welfare Education
Foreign Aid Regions Industry Law and Order

Import Spending (negative)
Goods and services bought from abroad – represents an outflow of funds from the UK (reduces AD)

Export Earnings (Positive)
Goods and services sold abroad – represents a flow of funds into the UK (raises AD)

Key variables

Macroeconomic policy

Fiscal Policy Government Income (taxes and borrowing)
Government Spending

Monetary Policy Interest Rates (Bank of England)

Aggregate Supply (AS)

Capacity of the Economy
Costs of Production Technology Education and Training Incentives Tax regime Capital stock Productivity Labour Market

Aggregate Supply Inflation AS
Between Y1 and Yf, increases in capacity are possible but the nearer the economy gets to Yf, the more problems are experienced with acquiring resources to boost production (production bottlenecks) especially labour skills shortages. An output level of Y1 would suggest the economy is working below full capacity and there would be widespread unemployment Yf represents ‘Full Employment Output – at this point the economy is working to full capacity and cannot produce any more The shape of the AS curve is important in determining the outcome in the economy This shape reflects a Keynesian view of the AS curve. Economy starts to overheat Y1 Yf Real National Income

Aggregate Supply Inflation AS1 AS2 Yf1 Yf2 Real National Income
Increases in capacity can occur as a result of a shift in AS (akin to a shift outwards of the Production Possibility Frontier) (PPF) Yf1 Yf2 Real National Income

Aggregate Supply Inflation LRAS Yf Real National Income
This is because they believe that in the long run, there will be no unemployment of resources because markets will clear, thus whatever the rate of inflation, firms will supply the maximum capacity of the economy. Classical economists assume the long run aggregate supply curve (LRAS) is vertical (perfectly inelastic). Yf Real National Income

Aggregate Supply AS Inflation Real National Income
For our analysis, we will assume the AS curve looks like this! Real National Income

A shift in the AD curve to AD1 as a result of a change in any or all of the factors affecting AD would increase growth, reduce unemployment but at a cost of higher inflation (a trade-off) Inflation In this situation, the economy would be operating at less than capacity, there would be unemployment and the economy might be growing only slowly. 2.5% 2.0% AD 1 AD Y1 Y2 Yf Real National Income

Further increases in AD would lead to successively smaller increases in growth and employment at the cost of ever higher inflation. Inflation 3.5% AD2 2.5% 2.0% AD1 AD Y1 Y2 Yf Y3 Real National Income