📚 Price Elasticity of Demand Explained
Price elasticity of demand measures how much the quantity demanded of a good changes when its price changes. Think about it: if the price of your favorite candy bar doubles, are you still going to buy it? Probably not as much! That's elasticity in action.
📈 Income Elasticity of Demand Explained
Income elasticity of demand, on the other hand, looks at how the quantity demanded changes when your income changes. If you get a raise, will you buy more of a certain good, less of it, or about the same amount? This helps economists classify goods as normal or inferior.
🆚 Price Elasticity vs. Income Elasticity: A Side-by-Side Comparison
| Feature |
Price Elasticity of Demand |
Income Elasticity of Demand |
| Definition |
Measures the responsiveness of quantity demanded to a change in price. |
Measures the responsiveness of quantity demanded to a change in consumer income. |
| Formula |
$ \frac{\% \text{ Change in Quantity Demanded}}{\% \text{ Change in Price}} $ |
$ \frac{\% \text{ Change in Quantity Demanded}}{\% \text{ Change in Income}} $ |
| Focus |
Price changes |
Income changes |
| Units |
Dimensionless (percentage change divided by percentage change) |
Dimensionless (percentage change divided by percentage change) |
| Significance |
Helps businesses understand how price changes will affect sales. |
Helps understand the nature of goods (normal, inferior, luxury). |
✨ Key Takeaways for AP Micro
- 📏Price Elasticity: Measures sensitivity to price changes.
- 💰Income Elasticity: Measures sensitivity to changes in consumer income.
- ➕Normal Goods: 🍏 A positive income elasticity indicates a normal good (demand increases with income).
- ➖Inferior Goods: 🍜 A negative income elasticity indicates an inferior good (demand decreases with income).
- 💎Luxury Goods: 🥂 Income elasticity > 1 often signifies a luxury good (demand increases more than proportionally with income).