What is aggregate demand in economics?

Aggregate demand is calculated using the formula AD = C + I + G + (X – M), where C is consumer expenditure, I is investment, G is government spending, and (X – M) is net exports. Each component can independently shift the AD curve.

The AD curve slopes downward from left to right. As the price level falls, real wealth increases, exports become more competitive, and lower interest rates stimulate borrowing — all of which increase the quantity of real output demanded.

In the UK, government spending (G) rose sharply during the Covid-19 pandemic through schemes such as furlough, directly boosting AD. Changes in UK interest rates set by the Bank of England also influence consumer borrowing and investment, shifting AD.

1. →(4 marks) Define aggregate demand and state its four components.
2. →(8 marks) Explain two factors that could cause aggregate demand to increase in the UK economy.
3. →(12 marks) Using a diagram, analyse the impact of a rise in consumer confidence on the UK's price level and real output.
4. →(20 marks) Evaluate the extent to which an increase in government spending is the most effective way to raise aggregate demand in the UK.
5. →(25 marks) "Consumer expenditure is the most important component of aggregate demand." Assess this view with reference to the UK economy.

• →Always define aggregate demand in your opening sentence using the formula AD = C + I + G + (X – M), as examiners award the definition mark independently of your subsequent analysis.
• →Distinguish clearly between a movement along the AD curve (caused by a change in the price level) and a shift of the AD curve (caused by a change in a component such as investment or government spending).
• →Show any AD diagram with clearly labelled axes (Price Level on the vertical axis, Real Output/GDP on the horizontal axis) and indicate whether the curve shifts left or right.
• →Avoid stating that "a rise in interest rates increases AD" — higher interest rates raise the cost of borrowing, which reduces consumer spending and investment, shifting AD to the left.
• →Include a specific UK example when explaining components of AD, such as referencing Bank of England interest rate decisions or UK government fiscal policy, to access higher mark bands.

Aggregate Demand (AD): The total demand for goods and services within an economy at a given price level over a given time period, expressed as AD = C + I + G + (X – M).

Consumer Expenditure (C): Household spending on goods and services, typically the largest component of AD in the UK, influenced by income, interest rates, and consumer confidence.

Investment (I): Spending by firms on capital goods such as machinery and infrastructure, influenced by interest rates, business confidence, and expected future returns.

Government Spending (G): Expenditure by the government on public services and infrastructure, representing a direct injection into the circular flow of income.

Net Exports (X – M): The value of exports minus the value of imports; a positive figure (trade surplus) adds to AD, while a negative figure (trade deficit) reduces it.

Shift in the AD Curve: A movement of the entire AD curve to the left or right, caused by a change in any component of AD other than the price level, such as a change in consumer confidence or government spending.