1.2.1
Elasticities of Demand
Test your knowledge with free interactive questions on Seneca — used by over 10 million students.
Elasticity
Elasticity measures the responsiveness of one variable to the change in another variable.

Price elasticity of demand (PED)
- Price elasticity = % change in quantity demanded ÷ % change in price.
- Elastic demand is where the PED > 1.
- Inelastic demand is where the PED < 1.
- Unitary elasticity is where the PED = 1.
- PED is almost always negative as an increase in price would result in a decrease in demand. But you may see some questions refer to it as positive for ease.

Income elasticity of demand (YED)
- Income elasticity of demand = % change in quantity demanded ÷ % change in income.
- Normal goods have a positive income elasticity, YED > 0 (income rises; demand increases).
- Inferior goods have negative income elasticity, YED < 0 (income rises; demand decreases).
- For example, those with higher income may buy fewer burgers and more steaks. Burgers in this case are an inferior good.
- YED can be positive or negative.

Cross-price elasticity of demand (XED)
- Cross-price elasticity of demand is when a change in the price of one good can change the quantity demanded of another.
- Cross-price elasticity of demand = % change in quantity demanded of good A ÷ % change in the price of good B.
- XED is positive if the goods are substitutes and negative if the goods are complements - you can work this out for yourself but also try to remember it!
- If XED is close to zero this would suggest that the goods are unrelated.
Complement Goods vs Substitute Goods
The cross-price elasticity of demand (XED) for complements is negative because a fall in the price of one good will increase the quantity demanded for the other good.

Complement goods
- For complements, a fall in the price of one good will lead to an increase in the quantity demanded for the other good. Complements have negative cross-price elasticities of demand.
- E.g. peanut butter and bread.
- E.g ice cream and sun cream.
- XED < 0

Substitute goods
- For, substitutes, a fall in the price of one will lead to a fall in the quantity demanded of the other. Substitutes have positive cross elasticities of demand.
- E.g. coffee and tea.
- XED > 0

Independent goods
- Independent goods have a cross-price elasticity of demand of zero.
- E.g donkeys and ice cream.
- XED = 0
1Microeconomics
1.1Competitive Markets: Demand & Suply
1.2Elasticity
1.3Government Intervention
1.4Market Failure
1.4.1Types of Market Failure1.4.2Introduction to Externalities1.4.3Negative Externalities1.4.4Policy for Negative Externalities1.4.5Positive Externalities1.4.6The Deadweight Welfare Loss of Externalities1.4.7Case Study - The Externalities of Education1.4.8Public Goods & the Free-Rider Problem1.4.9Asymmetric Information1.4.10End of Topic Test - Market Failure1.4.11Application Questions - Market Failure
1.5HL: Theory of the Firm & Market Structures
2Macroeconomics
2.1The Level of Overall Economic Activity
2.2Aggregate Demand & Aggregate Supply
2.2.1The Aggregate Demand Curve2.2.2Components of Aggregate Demand2.2.3Shape of the Aggregate Demand Curve2.2.4Shifts in Aggregate Demand2.2.5IB Multiple Choice - Aggregate Demand2.2.6Short & Long-Run Aggregate Supply2.2.7Alternative Models of LRAS2.2.8Equilibrium in the AD-AS Model2.2.9Output Gaps & the AD-AS Model
2.3Macroeconomic Objectives
2.3.1Introduction to Unemployment2.3.2Limitations of Unemployment2.3.3Types of Unemployment2.3.4Causes & Impact of Unemployment2.3.5Defining Inflation2.3.6Measuring Inflation2.3.7Use of Index Numbers2.3.8The Consumer Price Index2.3.9Consequences of Inflation2.3.10Causes of Inflation2.3.11Inflation & Unemployment Tradeoff2.3.12The Short-Run Phillips Curve2.3.13The Long-Run Phillips Curve
2.4Economic Growth, Poverty & Inequality
2.5Fiscal Policy
2.6Monetary Policy
2.7Supply-Side Policies
3The Global Economy
3.1International Trade
3.2Exchange Rates
3.3The Balance of Payments
3.4Economic Integration
3.5Terms of Trade
3.6Economic Development
3.7The Role of Domestic & International Factors
3.8The Role of International Trade
3.9The Role of Foreign Aid
Jump to other topics
1Microeconomics
1.1Competitive Markets: Demand & Suply
1.2Elasticity
1.3Government Intervention
1.4Market Failure
1.4.1Types of Market Failure1.4.2Introduction to Externalities1.4.3Negative Externalities1.4.4Policy for Negative Externalities1.4.5Positive Externalities1.4.6The Deadweight Welfare Loss of Externalities1.4.7Case Study - The Externalities of Education1.4.8Public Goods & the Free-Rider Problem1.4.9Asymmetric Information1.4.10End of Topic Test - Market Failure1.4.11Application Questions - Market Failure
1.5HL: Theory of the Firm & Market Structures
2Macroeconomics
2.1The Level of Overall Economic Activity
2.2Aggregate Demand & Aggregate Supply
2.2.1The Aggregate Demand Curve2.2.2Components of Aggregate Demand2.2.3Shape of the Aggregate Demand Curve2.2.4Shifts in Aggregate Demand2.2.5IB Multiple Choice - Aggregate Demand2.2.6Short & Long-Run Aggregate Supply2.2.7Alternative Models of LRAS2.2.8Equilibrium in the AD-AS Model2.2.9Output Gaps & the AD-AS Model
2.3Macroeconomic Objectives
2.3.1Introduction to Unemployment2.3.2Limitations of Unemployment2.3.3Types of Unemployment2.3.4Causes & Impact of Unemployment2.3.5Defining Inflation2.3.6Measuring Inflation2.3.7Use of Index Numbers2.3.8The Consumer Price Index2.3.9Consequences of Inflation2.3.10Causes of Inflation2.3.11Inflation & Unemployment Tradeoff2.3.12The Short-Run Phillips Curve2.3.13The Long-Run Phillips Curve
2.4Economic Growth, Poverty & Inequality
2.5Fiscal Policy
2.6Monetary Policy
2.7Supply-Side Policies
3The Global Economy
3.1International Trade
3.2Exchange Rates
3.3The Balance of Payments
3.4Economic Integration
3.5Terms of Trade
3.6Economic Development
3.7The Role of Domestic & International Factors
3.8The Role of International Trade
3.9The Role of Foreign Aid
Practice questions on Elasticities of Demand
Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.
- 1Types of elasticity of demand:Fill in the list
- 2What is another way to describe elasticity?Multiple choice
- 3Goods and income elasticity of demand (YED):Fill in the list
- 4Why might the demand for burgers go up in a recession?Multiple choice
- 5Examples of substitute goods:Fill in the list
Unlock your full potential with Seneca Premium
Unlimited access to 10,000+ open-ended exam questions
Mini-mock exams based on your study history
Unlock 800+ premium courses & e-books