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 patterns for different goods as incomes vary.
- Income Elasticity of Demand (YED) — the responsiveness of quantity demanded to a change in consumer 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: Public transport may see increased demand during a recession.
- Engel Curve — a graph showing how demand for a good changes with income Example: The curve for normal goods slopes upwards.
- Necessities — normal goods with 0 < YED < 1, indicating inelastic demand Example: Basic food items like bread.
- Luxury Goods — normal goods with YED > 1, indicating elastic demand Example: High-end electronics.
Exam Tips
Key Definitions to Remember
- Income Elasticity of Demand (YED)
- Normal Goods
- Inferior Goods
- Engel Curve
Common Confusions
- Confusing normal goods with necessities
- Misinterpreting the sign of YED for normal and inferior goods
Typical Exam Questions
- What is YED and how is it calculated? YED is calculated as the percentage change in quantity demanded divided by the percentage change in income.
- How does YED affect the demand curve? A positive YED shifts the demand curve right with income increase; a negative YED shifts it left.
- Why is YED important for firms? It helps firms predict changes in demand based on income changes.
What Examiners Usually Test
- Understanding of YED and its calculation
- Ability to interpret YED values for different goods
- Application of YED in real-world scenarios, such as sectoral changes in the economy