The Market: Demand, Supply and Price (Edexcel 9BS0 1.2)
Topic 1.2 explains how prices are set by the interaction of demand and supply. It is the most economics-flavoured part of Theme 1, and examiners use it to test whether students can read and interpret supply and demand diagrams under time pressure.
What shifts demand
Demand is the quantity customers are willing and able to buy at a given price. A change in price causes movement along the demand curve; other factors shift the whole curve. The specification lists the main shifters:
- Changes in the price of substitutes and complements — when meal-deal prices rose at rivals, cheaper alternatives gained custom.
- Incomes — the cost-of-living squeeze from 2022 pushed shoppers towards discounters, lifting demand at Aldi and Lidl while premium ranges suffered.
- Tastes and fashion — demand for meat-free products surged then cooled in the mid-2020s, forcing supermarkets to trim vegan ranges.
- Advertising and branding, demographics, and external shocks such as weather or seasonality — Greggs sells noticeably more hot food in cold months and pushes iced drinks in summer.
In the exam, name the factor, state the direction of the shift, and explain the effect on price and quantity — three quick steps that earn the marks.
What shifts supply
Supply is the quantity producers are willing to offer at each price. The curve shifts when production conditions change:
- Costs of production — the price of cocoa roughly tripled during 2024 after poor West African harvests, cutting the profitability of chocolate at every price and pushing bar prices up and sizes down across UK supermarkets.
- Technology — automation in food manufacturing raises output at lower unit cost, shifting supply outward.
- Indirect taxes and subsidies — a higher duty raises costs and reduces supply; a subsidy does the opposite.
- Natural factors — weather, disease and harvest failures hit agricultural supply hardest.
Notice the language: a cost increase shifts supply left (less offered at each price), which raises the equilibrium price and lowers quantity. Students who confuse shifts of the curve with movements along it lose easy marks, so always ask first: did price change, or did something else change?
Equilibrium, excess demand and excess supply
The equilibrium price is where demand equals supply and the market clears. Away from it, pressure pushes price back:
- Excess demand — at a price below equilibrium, buyers want more than sellers offer. If fans demand 1,200 tickets but only 800 are available at £40, the 400-ticket shortage lets sellers raise prices, which is exactly why resale prices for sold-out concerts climb.
- Excess supply — above equilibrium, sellers offer more than buyers take. Supermarkets discount short-dated stock precisely to clear this surplus before it becomes waste.
A worked reading: if demand shifts right while supply is unchanged, both equilibrium price and quantity rise; if supply shifts left at the same time — as with cocoa in 2024 — price rises further while quantity may fall. Practise sketching these two-shift diagrams, because Edexcel data questions often combine a demand-side and a supply-side event in the same extract and ask for the combined effect.
Key terms
Practice questions
Explain one factor that could increase demand for a supermarket's own-label ranges. [4 marks]
Model answer guidance: Choose a shifter such as falling real incomes. Build the chain: squeezed household budgets make shoppers trade down from brands, own-label products are close substitutes at lower prices, so demand for them rises at every price point. Apply to the shift towards discounters and value ranges seen during the cost-of-living squeeze.
Explain one likely effect on the market for chocolate of a sharp rise in the world price of cocoa. [4 marks]
Model answer guidance: State that higher input costs shift supply left. Develop: producing each bar is now more expensive, so manufacturers offer less at each price, pushing the equilibrium price up and quantity down. Apply with the 2024 cocoa spike, when UK chocolate prices rose and bar sizes shrank — an example of the same effect through shrinkflation.
Discuss the likely impact on a premium food brand of a prolonged fall in consumer incomes. [8 marks]
Model answer guidance: Analyse the demand-side effect: premium foods are income-sensitive, so demand shifts left, cutting sales volume and possibly forcing discounting that damages brand image. Counter-analyse: impact depends on customer loyalty and the size of the price gap to alternatives; some premium treats hold up as small affordable luxuries. Conclude that the severity rests on how income-elastic the specific product is.
Assess the usefulness of supply and demand analysis to a retailer setting prices in a fast-moving market. [10 marks]
Model answer guidance: For: the framework predicts the direction of price pressure when costs or tastes change, helping the retailer anticipate rather than react — cocoa costs feeding through to chocolate prices is a clean example. Against: real pricing also reflects branding, psychological price points and rival reactions, and curves cannot be observed precisely. Judgement: strong as a directional guide, weak as a precise pricing tool.
Assess whether changes in supply or changes in demand are more important in explaining recent UK food price rises. [12 marks]
Model answer guidance: Supply side: input cost shocks — energy in 2022, cocoa in 2024 — shifted supply left across categories, the main driver of grocery inflation. Demand side: demand shifts explain relative winners, such as discounters gaining as shoppers traded down, more than the general price level. A top answer separates the general rise (supply-driven) from changes in spending patterns (demand-driven) and concludes supply factors dominated, with demand shaping who gained and lost.
Examiner tips
- Always state the direction of the shift and the resulting change in both price and quantity — one-word answers like 'demand rises' leave marks on the table.
- Distinguish a movement along a curve (caused only by price) from a shift of the curve (caused by anything else); examiners test this distinction every series.
- When an extract contains both a cost change and a taste change, deal with the two shifts separately before combining them in your conclusion.
In The Business School simulation your students make these exact decisions in a live market against rival firms — every choice mapped to the specification. Free teacher demo, no installs, students join with a PIN.