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What are the components of aggregate demand, and what determines each one?

2.2 Aggregate demand: the components of AD (consumption, investment, government spending and net exports), the determinants of each, and why the AD curve slopes downward and shifts.

An OCR H460 answer to aggregate demand, covering the four components (consumption, investment, government spending and net exports), the determinants of each, why the AD curve slopes downward, and the causes of shifts in aggregate demand.

Generated by Claude Opus 4.810 min answer

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  1. What this dot point is asking
  2. The components of aggregate demand
  3. The determinants of each component
  4. Shifts in aggregate demand
  5. Examples in context
  6. Try this

What this dot point is asking

OCR wants you to define aggregate demand and its four components, to explain what determines each component, to explain why the AD curve slopes downward, and to identify the causes of shifts in aggregate demand.

The components of aggregate demand

In the UK, consumption is by far the largest component (around 60 per cent of AD), so changes in consumer spending have the biggest direct effect. Net exports are often negative (a trade deficit), which subtracts from AD.

The determinants of each component

  • Consumption (C). Depends on real disposable income (the main driver), consumer confidence, interest rates (lower rates encourage borrowing and discourage saving), wealth effects (rising house or share prices), and the availability of credit. The marginal propensity to consume measures how much of extra income is spent.
  • Investment (I). The most volatile component. Depends on interest rates (the cost of borrowing), business confidence and expected demand (Keynes's "animal spirits"), the rate of technological change, corporation tax and incentives, and retained profits. The accelerator links investment to the rate of change of output.
  • Government spending (G). Determined by fiscal policy and the stage of the economic cycle (automatic stabilisers raise spending in downturns).
  • Net exports (X - M). Depend on the exchange rate (a weaker pound boosts exports and curbs imports), relative inflation and competitiveness, and incomes at home and abroad (higher foreign income raises exports; higher domestic income raises imports).

Shifts in aggregate demand

The AD curve shifts right when a component rises for a reason other than the domestic price level: rising confidence, lower interest rates, a fiscal expansion, a weaker pound or stronger world growth. It shifts left in the opposite cases. Distinguish a shift of AD (a change in a component's determinant) from a movement along AD (a change in the domestic price level).

Examples in context

  • The pandemic demand shock. Lockdowns cut consumption and investment sharply (AD left), prompting large fiscal and monetary support to shift AD back.
  • Interest-rate rises. The 2022 to 2023 tightening raised borrowing costs, dampening consumption and investment to cool AD and inflation.
  • A weaker pound. Sterling's falls have boosted export competitiveness (raising X) while making imports dearer, affecting net exports.

Try this

Q1. State the four components of aggregate demand. [3 marks]

  • Cue. Consumption, investment, government spending and net exports (C+I+G+(X−M)C + I + G + (X - M)).

Q2. Explain why investment is the most volatile component of AD. [4 marks]

  • Cue. It depends heavily on confidence and expected demand, which swing sharply, and on interest rates and the accelerator.

Exam-style practice questions

Practice questions written in the style of OCR exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

OCR H460/02 20204 marksAggregate demand is made up of C=£900C = \pounds 900bn, I=£200I = \pounds 200bn, G=£350G = \pounds 350bn, exports =£400= \pounds 400bn and imports =£450= \pounds 450bn. Calculate the level of aggregate demand and state the value of net exports.
Show worked answer →

A short calculate question using AD=C+I+G+(X−M)AD = C + I + G + (X - M).

Net exports are exports minus imports: X−M=400−450=−£50X - M = 400 - 450 = -\pounds 50bn (a trade deficit on this measure).

AD=900+200+350+(−50)=£1,400AD = 900 + 200 + 350 + (-50) = \pounds 1{,}400bn.

Markers reward the net-exports figure (−£50-\pounds 50bn), the substitution into the formula, and the aggregate-demand total (£1,400\pounds 1{,}400bn). A common slip is to add imports rather than subtract them.

OCR H460/02 202212 marksAssess the factors that determine the level of investment in an economy.
Show worked answer →

A levels-of-response question. Knowledge and application: define investment (spending on capital goods) and explain it is the most volatile component of AD. Set out determinants: interest rates (the cost of borrowing), business confidence and expected demand ('animal spirits'), the rate of technological change, corporation tax and government incentives, and the level of retained profit.

Analysis: develop how a fall in interest rates or rising confidence raises investment, shifting AD right.

Evaluation: weigh which determinant matters most and when. Confidence and expected demand may dominate (firms will not invest in a slump even at low rates), and the accelerator links investment to the rate of change of output. Conclude with a supported judgement that expectations and demand are often the key drivers, with interest rates important but not decisive.

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