Aggregate Demand: Components and Determinants
Aggregate demand (AD) is the total planned spending on domestically produced goods and services in an economy at a given price level, over a given time period.
Before you start
Make sure you're comfortable with these topics first:
Method
- Learn the AD equation, AD = C + I + G + (X - M), and what each letter stands for.
- Learn the reasons AD slopes downward (the real balance/wealth effect, the interest rate effect and the international trade effect), so a question asking why AD slopes downward is answered from this list, not from a shift.
- For each component, learn its main determinants: C (disposable income, interest rates, consumer confidence, wealth), I (interest rates, business confidence, corporation tax, access to credit), G (government policy decisions), X-M (the exchange rate, incomes abroad, relative inflation rates, trade barriers).
- Distinguish a movement along AD, caused only by a change in the price level, from a shift of the whole AD curve, caused by a change in a non-price determinant of C, I, G or X-M.
- Draw the diagram, shift AD in the correct direction, and read off the resulting change in the price level and real output where it meets AS.
- Explain any given event as a chain: identify which component of AD is affected, state the direction of the shift, state the new equilibrium price level and output, and reference the multiplier if the change is an injection or withdrawal.
- Evaluate using the size of the shift, the state of the economy relative to full employment, and whether other components might move in the opposite direction and partly offset the effect.
Worked example
The central bank cuts its base interest rate. Explain the chain of effects this is likely to have on aggregate demand, and show the effect on an AD/AS diagram.
- A lower interest rate reduces the cost of borrowing and the reward for saving, so households are likely to borrow and spend more, and save less, raising consumption (C).
- A lower interest rate also reduces the cost of finance for firms, making more investment projects profitable, so planned investment (I) rises.
- A lower interest rate can also cause the exchange rate to depreciate, as lower returns make the currency less attractive to overseas savers, making exports relatively cheaper and imports relatively more expensive, raising net exports (X-M).
- Since C, I and X-M have all risen, AD = C + I + G + (X-M) rises, shifting the AD curve rightward from AD1 to AD2.
- On the diagram, the new equilibrium, where AD2 meets SRAS, shows a higher price level and higher real output than before.
- The overall size of the effect on real output versus the price level depends on how much spare capacity the economy has: more spare capacity means more of the effect falls on output rather than price.
Practice questions
Try each question, then tap to reveal the answer.
Q1Write out the equation for aggregate demand.Show answer
Answer: AD = C + I + G + (X - M).
Q2State the three reasons the AD curve slopes downward.Show answer
Answer: The real balance (wealth) effect, the interest rate effect and the international trade effect.
Q3Give two determinants of consumer spending (C), other than the interest rate.Show answer
Answer: Disposable income and consumer confidence, or household wealth.
Q4If the pound depreciates against other currencies, what is the likely effect on net exports (X-M), and why?Show answer
Answer: Net exports are likely to rise, because a weaker pound makes UK exports cheaper for foreign buyers and imports more expensive for UK buyers.
Q5Distinguish between a movement along the AD curve and a shift of the AD curve.Show answer
Answer: A movement along AD is caused only by a change in the price level; a shift of the whole AD curve is caused by a change in a non-price determinant of C, I, G or X-M.
Q6State one reason a rise in corporation tax might reduce investment (I).Show answer
Answer: It reduces the after-tax profit firms can expect from an investment project, making fewer projects worth undertaking, or it reduces retained profit available to finance investment.
Q7If AD is 900bn and its components are C = 550bn, I = 150bn, G = 180bn and imports are 100bn, what is the value of exports?Show answer
Answer: 900 = 550 + 150 + 180 + (X - 100), so 900 = 880 + X - 100, giving X = 120bn.
Exam-style questions
Written in the style of a A Level Economics exam paper, with a full mark scheme.
Explain two reasons why a rise in consumer confidence is likely to increase aggregate demand.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 6 available
Evaluate the view that a depreciation of the pound is the most significant cause of an increase in aggregate demand.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 15 available
See real A Level Economics past-paper questions, with official mark schemes →
Free printable worksheet
Want more practice on paper? Download the aggregate demand: components and determinants worksheet pack - 5 pages of exam-style questions with a full mark scheme. One email opens every download in this browser for 14 days - no account, no card. Print it for personal and classroom use.
Next topics
Not quite what you needed?
Tell us what is missing on aggregate demand: components and determinants, or which topic to write up next. Every request is read, and we reply to every one.
Build a full practice pack.
This topic is one of hundreds in the library - pick the ones a student needs and generate a printable PDF in minutes.