Cross Elasticity of Demand (XED)

Active learning works here because XED is best understood through concrete examples and calculations. Students need to experience how the price change of one good shifts demand for another to grasp the practical meaning of positive, negative, and zero values.

• Year 12
• Economics
• 4 activities
• 20 min–40 min

Learning Objectives

1. Calculate the cross elasticity of demand for various pairs of goods using provided price and quantity data.
2. Classify pairs of goods as substitutes, complements, or unrelated based on their calculated XED values.
3. Explain the strategic implications of positive and negative XED values for firms in pricing and marketing decisions.
4. Predict the likely change in demand for one product when the price of a related product changes, using XED knowledge.

Case Study Analysis

⏱ 25 min·Pairs

Pairs Calculation: XED Data Sheets

Provide printed tables with price and quantity data for related goods like butter and spreads. Pairs compute XED values, classify goods, and note business advice in a shared table. End with pairs sharing one insight with the class.

Prepare & details

Analyze how cross-price elasticity helps classify goods as substitutes or complements.

Facilitation Tip: During Pairs Calculation: XED Data Sheets, circulate and listen for pairs explaining why a negative XED means complements, not substitutes.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Case Study Analysis

⏱ 35 min·Small Groups

Small Groups: Market Simulation Cards

Distribute cards assigning groups as firms selling substitutes or complements. One group announces a price change; others adjust demand quantities using given XED values and record on a class chart. Rotate roles twice.

Prepare & details

Explain the implications of positive and negative XED values for businesses.

Facilitation Tip: In Small Groups: Market Simulation Cards, assign each group a unique pair of goods so the class can compare diverse outcomes.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Case Study Analysis

⏱ 40 min·Whole Class

Whole Class: Supermarket Data Debate

Project real UK supermarket sales data after a price rise on one product, such as energy drinks. Class calculates XED for potential related items and debates classifications in a structured vote.

Prepare & details

Predict the impact of a price change in one product on the demand for a related product.

Facilitation Tip: In Whole Class: Supermarket Data Debate, select two student groups with opposing views to present their reasoning before the class votes on the most plausible impact.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Case Study Analysis

⏱ 20 min·Individual

Individual: Case Study Prediction

Students receive a business scenario, like a coffee shop facing a tea price hike. They calculate XED from provided data, predict demand changes, and write a short pricing recommendation.

Prepare & details

Analyze how cross-price elasticity helps classify goods as substitutes or complements.

Facilitation Tip: For Individual: Case Study Prediction, require students to show their formula steps and sign interpretation before writing their final prediction.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Teaching This Topic

Teach XED by starting with pairs of goods students know well, like coffee and tea or printers and ink. Use real supermarket data to show how price changes translate into demand shifts. Avoid abstract formulas at first; let students derive the concept from familiar examples. Research shows that sorting activities and role-play reduce confusion between XED and PED more effectively than lectures alone.

What to Expect

By the end of these activities, students will calculate XED accurately, classify pairs as substitutes or complements, and explain real-world demand shifts using economic reasoning. They should connect the sign and size of XED to market behavior.

Watch Out for These Misconceptions

Common Misconception

During Pairs Calculation: XED Data Sheets, watch for students labeling all related goods as substitutes.

What to Teach Instead

Have pairs sort their calculated XED values into three labeled columns: substitutes (positive), complements (negative), unrelated (near zero), using everyday examples like hot dogs and buns as anchors.

Common Misconception

During Small Groups: Market Simulation Cards, watch for students treating XED as a measure of a good's own price change.

What to Teach Instead

At each station, ask groups to clearly label Good A and Good B on their cards before calculating, and then discuss how the price change of Good B affects demand for Good A.

Common Misconception

During Whole Class: Supermarket Data Debate, watch for students assuming that a large XED value always means a strong relationship regardless of sign.

What to Teach Instead

During the debate, have students graph their calculated XED values on a number line, labeling substitutes to the right and complements to the left, to visualize the role of the sign.

Assessment Ideas

Quick Check

After Pairs Calculation: XED Data Sheets, collect one calculation sheet from each pair and check for correct formula application, sign interpretation, and classification of goods as substitutes or complements.

Discussion Prompt

During Whole Class: Supermarket Data Debate, listen for students using XED terminology (substitutes, complements) and sign values to justify their predictions about demand shifts for electric cars and public transport.

Exit Ticket

After Individual: Case Study Prediction, collect exit tickets to check that each student provides one substitute and one complement example with a brief explanation of the sign of XED for each pair.

Extensions & Scaffolding

• Challenge early finishers to create a new scenario involving three goods, where one is unrelated to the other two, and calculate all possible XEDs.
• Scaffolding for struggling students: Provide a partially completed calculation table with missing steps or a word bank for substitute, complement, unrelated.
• Deeper exploration: Have students research an industry where cross elasticity played a key role in pricing strategy, such as streaming services and cable TV, and present findings.

Key Vocabulary

Cross Elasticity of Demand (XED)	A measure of how the quantity demanded of one good responds to a change in the price of another good. It helps classify the relationship between goods.
Substitutes	Goods that can be used in place of each other. An increase in the price of one leads to an increase in the demand for the other, resulting in a positive XED.
Complements	Goods that are often consumed together. An increase in the price of one leads to a decrease in the demand for the other, resulting in a negative XED.
Unrelated Goods	Goods for which the demand for one is not significantly affected by a change in the price of the other. These typically have an XED value close to zero.