Study Notes
Income Elasticity of Demand (YED) measures how the quantity demanded of a good changes in response to a change in consumer income. It helps understand demand shifts for normal and inferior goods.
- Income Elasticity of Demand (YED) — the responsiveness of quantity demanded to a change in income Example: If income increases and demand for coffee rises, coffee is a normal good with positive YED.
- Normal Goods — goods with a positive YED, meaning demand increases as income increases Example: Luxury cars have a high positive YED.
- Inferior Goods — goods with a negative YED, meaning demand decreases as income increases Example: Instant noodles may have a negative YED.
- Engel Curve — a graph showing how demand for a good changes with income Example: The curve for luxury goods is upward sloping with a flatter slope.
Exam Tips
Key Definitions to Remember
- Income Elasticity of Demand (YED)
- Normal Goods
- Inferior Goods
- Engel Curve
Common Confusions
- Confusing normal goods with inferior goods
- Misinterpreting the sign of YED as the magnitude
Typical Exam Questions
- What is YED? YED is the responsiveness of quantity demanded to a change in income.
- How does YED differ for normal and inferior goods? Normal goods have a positive YED, while inferior goods have a negative YED.
- What does a YED greater than 1 indicate? It indicates income elastic demand, typical for luxury goods.
What Examiners Usually Test
- Ability to calculate and interpret YED values
- Understanding the implications of YED for different types of goods
- Application of YED in real-world economic scenarios