Data and market analysis: interpreting business and market data, and price elasticity of demand and income elasticity of demand, including their calculation and use in decision making.

What this dot point is asking

WJEC Unit 3 opens with analysing data and the elasticities of demand. You need to interpret business and market data and to calculate and use price elasticity of demand (PED) and income elasticity of demand (YED). This is a quantitative, decision-focused topic, so the marks are for the calculation, the correct interpretation (elastic or inelastic), and the implication for revenue or strategy.

The answer

Interpreting business and market data

A firm that reads its data well can identify a growing or declining product, a rising cost, or a shift in the market, and act before rivals do. Good analysis also questions the data: how recent is it, how was it collected, and is the sample representative? Numbers alone do not decide; they inform judgement.

Price elasticity of demand

The link to revenue is the key exam point:

• Inelastic demand: a price rise increases total revenue (quantity falls only a little), and a price cut reduces it.
• Elastic demand: a price cut increases total revenue (quantity rises a lot), and a price rise reduces it.

Demand is more inelastic when a product has few substitutes, is a necessity, is habit-forming, takes a small share of income, or has strong brand loyalty; it is more elastic when substitutes are plentiful, the product is a luxury, or it takes a large share of income.

Income elasticity of demand

Income elasticity of demand (YED) measures how responsive demand is to a change in consumers' income: YED = % change in quantity demanded / % change in income. Its sign matters:

• Positive YED = a normal good (demand rises as income rises). A YED above 1 marks a luxury (demand rises proportionately more than income).
• Negative YED = an inferior good (demand falls as income rises, for example budget products people switch away from as they get richer).

Firms use YED to plan for the economic cycle: luxury goods boom in growth and slump in recession, while inferior goods can be more resilient in a downturn.

Examples in context

Example 1. An inelastic necessity. A firm selling a staple product with few substitutes and strong brand loyalty faces inelastic demand. When it raises the price modestly, quantity falls only slightly, so total revenue rises. The example shows why firms with inelastic demand (established brands, necessities) can use price rises to lift revenue, while a firm with elastic demand cannot.

Example 2. Income elasticity over the economic cycle. A premium restaurant chain sells a luxury experience with a high positive YED, so its sales rise strongly when incomes grow but fall sharply in a recession as customers cut back. A budget retailer selling value goods (some inferior) is more resilient, even gaining custom as shoppers trade down. The example illustrates how YED helps firms anticipate the effect of the economy on demand and plan accordingly.

Try this

Q1. Define the term price elasticity of demand. [2 marks]

• Cue. A measure of the responsiveness of quantity demanded to a change in price, calculated as the percentage change in quantity demanded divided by the percentage change in price.

Q2. A product's price falls by 5% and demand rises by 15%. Calculate the PED and state whether demand is elastic or inelastic. [3 marks]

• Cue. PED = +15% / -5% = -3 (size 3). Greater than 1, so demand is price elastic.