Micro 11.28.13 elasticity concepts
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1. The document discusses the concept of elasticity and how it allows for more precise analysis of supply and demand. 2. It defines price elasticity of demand as the percentage change in quantity demanded given a percentage change in price. Factors like availability of substitutes, necessity vs luxury goods, and time horizon determine if demand is more or less elastic. 3. The price elasticity of supply measures how much quantity supplied responds to price changes. Inelastic supply responds less than elastic supply to price changes.
![Copyright © 2004 South-Western/Thomson Learning
The Midpoint Method: A Better Way to
Calculate Percentage Changes and
Elasticities
• The midpoint formula is preferable when
calculating the price elasticity of demand
because it gives the same answer regardless of
the direction of the change.
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Micro 11.28.13 elasticity concepts
- 1. Copyright © 2004 South-Western Elasticity and Its Applications MICROECONOMICS Lecture 2 11.28.13
- 2. Copyright © 2004 South-Western/Thomson Learning Elasticity . . . • … allows us to analyze supply and demand with greater precision. • … is a measure of how much buyers and sellers respond to changes in market conditions
- 3. Copyright © 2004 South-Western/Thomson Learning THE ELASTICITY OF DEMAND • Price elasticity of demand is a measure of how much the quantity demanded of a good responds to a change in the price of that good. • Price elasticity of demand is the percentage change in quantity demanded given a percent change in the price.
- 4. Copyright © 2004 South-Western/Thomson Learning The Price Elasticity of Demand and Its Determinants • Availability of Close Substitutes • Necessities versus Luxuries • Definition of the Market • Time Horizon
- 5. Copyright © 2004 South-Western/Thomson Learning The Price Elasticity of Demand and Its Determinants • Demand tends to be more elastic : • the larger the number of close substitutes. • if the good is a luxury. • the more narrowly defined the market. • the longer the time period.
- 6. Copyright © 2004 South-Western/Thomson Learning Computing the Price Elasticity of Demand • The price elasticity of demand is computed as the percentage change in the quantity demanded divided by the percentage change in price. P r i c e e l a s t i c i t y o f d e m a n d = P e r c e n t a g e c h a n g e i n q u a n t i t y d e m a n d e d P e r c e n t a g e c h a n g e i n p r i c e
- 7. Copyright © 2004 South-Western/Thomson Learning • Example: If the price of an ice cream cone increases from $2.00 to $2.20 and the amount you buy falls from 10 to 8 cones, then your elasticity of demand would be calculated as: Computing the Price Elasticity of Demand P r i c e e l a s t i c i t y o f d e m a n d = P e r c e n t a g e c h a n g e i n q u a n t i t y d e m a n d e d P e r c e n t a g e c h a n g e i n p r i c e ( ) ( . . ) . 1 0 8 1 0 1 0 0 2 2 0 2 0 0 2 0 0 1 0 0 2 0 % 1 0 % 2 − × − × = =
- 8. Copyright © 2004 South-Western/Thomson Learning The Midpoint Method: A Better Way to Calculate Percentage Changes and Elasticities • The midpoint formula is preferable when calculating the price elasticity of demand because it gives the same answer regardless of the direction of the change. P r i c e e l a s t i c i t y o f d e m a n d = ( ) / [ ( ) / ] ( ) / [ ( ) / ] Q Q Q Q P P P P 2 1 2 1 2 1 2 1 2 2 − + − +
- 9. Copyright © 2004 South-Western/Thomson Learning The Midpoint Method: A Better Way to Calculate Percentage Changes and Elasticities • Example: If the price of an ice cream cone increases from $2.00 to $2.20 and the amount you buy falls from 10 to 8 cones, then your elasticity of demand, using the midpoint formula, would be calculated as: ( ) ( ) / ( . . ) ( . . ) / . . 1 0 8 1 0 8 2 2 2 0 2 0 0 2 0 0 2 2 0 2 2 2 % 9 5 % 2 3 2 − + − + = =
- 10. Copyright © 2004 South-Western/Thomson Learning The Variety of Demand Curves • Inelastic Demand • Quantity demanded does not respond strongly to price changes. • Price elasticity of demand is less than one. • Elastic Demand • Quantity demanded responds strongly to changes in price. • Price elasticity of demand is greater than one.
- 11. Copyright © 2004 South-Western/Thomson Learning Computing the Price Elasticity of Demand Demand is price elastic $5 4 Demand Quantity1000 50 -3 percent22- percent67 5.00)/2(4.00 5.00)-(4.00 50)/2(100 50)-(100 ED == + + = Price
- 12. Copyright © 2004 South-Western/Thomson Learning The Variety of Demand Curves • Perfectly Inelastic • Quantity demanded does not respond to price changes. • Perfectly Elastic • Quantity demanded changes infinitely with any change in price. • Unit Elastic • Quantity demanded changes by the same percentage as the price.
- 13. Copyright © 2004 South-Western/Thomson Learning The Variety of Demand Curves • Because the price elasticity of demand measures how much quantity demanded responds to the price, it is closely related to the slope of the demand curve.
- 14. Figure 1 The Price Elasticity of Demand Copyright©2003 Southwestern/Thomson Learning (a) Perfectly Inelastic Demand: Elasticity Equals 0 $5 4 Quantity Demand 1000 1. An increase in price . . . 2. . . . leaves the quantity demanded unchanged. Price
- 15. Figure 1 The Price Elasticity of Demand (b) Inelastic Demand: Elasticity Is Less Than 1 Quantity0 $5 90 Demand1. A 22% increase in price . . . Price 2. . . . leads to an 11% decrease in quantity demanded. 4 100
- 16. Figure 1 The Price Elasticity of Demand Copyright©2003 Southwestern/Thomson Learning 2. . . . leads to a 22% decrease in quantity demanded. (c) Unit Elastic Demand: Elasticity Equals 1 Quantity 4 1000 Price $5 80 1. A 22% increase in price . . . Demand
- 17. Figure 1 The Price Elasticity of Demand (d) Elastic Demand: Elasticity Is Greater Than 1 Demand Quantity 4 1000 Price $5 50 1. A 22% increase in price . . . 2. . . . leads to a 67% decrease in quantity demanded.
- 18. Figure 1 The Price Elasticity of Demand (e) Perfectly Elastic Demand: Elasticity Equals Infinity Quantity0 Price $4 Demand 2. At exactly $4, consumers will buy any quantity. 1. At any price above $4, quantity demanded is zero. 3. At a price below $4, quantity demanded is infinite.
- 19. Copyright © 2004 South-Western/Thomson Learning Total Revenue and the Price Elasticity of Demand • Total revenue is the amount paid by buyers and received by sellers of a good. • Computed as the price of the good times the quantity sold. TR = P x Q
- 20. Figure 2 Total Revenue Copyright©2003 Southwestern/Thomson Learning Demand Quantity Q P 0 Price P × Q = $400 (revenue) $4 100
- 21. Copyright © 2004 South-Western/Thomson Learning Elasticity and Total Revenue along a Linear Demand Curve • With an inelastic demand curve, an increase in price leads to a decrease in quantity that is proportionately smaller. Thus, total revenue increases.
- 22. Figure 3 How Total Revenue Changes When Price Changes: Inelastic Demand Copyright©2003 Southwestern/Thomson Learning Demand Quantity0 Price Revenue = $100 Quantity0 Price Revenue = $240 Demand $1 100 $3 80 An Increase in price from $1 to $3 … … leads to an Increase in total revenue from $100 to $240
- 23. Copyright © 2004 South-Western/Thomson Learning Elasticity and Total Revenue along a Linear Demand Curve • With an elastic demand curve, an increase in the price leads to a decrease in quantity demanded that is proportionately larger. Thus, total revenue decreases.
- 24. Figure 4 How Total Revenue Changes When Price Changes: Elastic Demand Copyright©2003 Southwestern/Thomson Learning Demand Quantity0 Price Revenue = $200 $4 50 Demand Quantity0 Price Revenue = $100 $5 20 An Increase in price from $4 to $5 … … leads to an decrease in total revenue from $200 to $100
- 25. Copyright © 2004 South-Western/Thomson Learning Elasticity of a Linear Demand Curve
- 26. Copyright © 2004 South-Western/Thomson Learning Income Elasticity of Demand • Income elasticity of demand measures how much the quantity demanded of a good responds to a change in consumers’ income. • It is computed as the percentage change in the quantity demanded divided by the percentage change in income.
- 27. Copyright © 2004 South-Western/Thomson Learning Computing Income Elasticity I n c o m e e l a s t i c i t y o f d e m a n d = P e r c e n t a g e c h a n g e i n q u a n t i t y d e m a n d e d P e r c e n t a g e c h a n g e i n i n c o m e
- 28. Copyright © 2004 South-Western/Thomson Learning Income Elasticity • Types of Goods • Normal Goods • Inferior Goods • Higher income raises the quantity demanded for normal goods but lowers the quantity demanded for inferior goods.
- 29. Copyright © 2004 South-Western/Thomson Learning Income Elasticity • Goods consumers regard as necessities tend to be income inelastic • Examples include food, fuel, clothing, utilities, and medical services. • Goods consumers regard as luxuries tend to be income elastic. • Examples include sports cars, furs, and expensive foods.
- 30. Copyright © 2004 South-Western/Thomson Learning THE ELASTICITY OF SUPPLY • Price elasticity of supply is a measure of how much the quantity supplied of a good responds to a change in the price of that good. • Price elasticity of supply is the percentage change in quantity supplied resulting from a percent change in price.
- 31. Figure 6 The Price Elasticity of Supply Copyright©2003 Southwestern/Thomson Learning (a) Perfectly Inelastic Supply: Elasticity Equals 0 $5 4 Supply Quantity1000 1. An increase in price . . . 2. . . . leaves the quantity supplied unchanged. Price
- 32. Figure 6 The Price Elasticity of Supply Copyright©2003 Southwestern/Thomson Learning (b) Inelastic Supply: Elasticity Is Less Than 1 110 $5 100 4 Quantity0 1. A 22% increase in price . . . Price 2. . . . leads to a 10% increase in quantity supplied. Supply
- 33. Figure 6 The Price Elasticity of Supply Copyright©2003 Southwestern/Thomson Learning (c) Unit Elastic Supply: Elasticity Equals 1 125 $5 100 4 Quantity0 Price 2. . . . leads to a 22% increase in quantity supplied. 1. A 22% increase in price . . . Supply
- 34. Figure 6 The Price Elasticity of Supply Copyright©2003 Southwestern/Thomson Learning (d) Elastic Supply: Elasticity Is Greater Than 1 Quantity0 Price 1. A 22% increase in price . . . 2. . . . leads to a 67% increase in quantity supplied. 4 100 $5 200 Supply
- 35. Figure 6 The Price Elasticity of Supply Copyright©2003 Southwestern/Thomson Learning (e) Perfectly Elastic Supply: Elasticity Equals Infinity Quantity0 Price $4 Supply 3. At a price below $4, quantity supplied is zero. 2. At exactly $4, producers will supply any quantity. 1. At any price above $4, quantity supplied is infinite.
- 36. Copyright © 2004 South-Western/Thomson Learning Determinants of Elasticity of Supply • Ability of sellers to change the amount of the good they produce. • Beach-front land is inelastic. • Books, cars, or manufactured goods are elastic. • Time period. • Supply is more elastic in the long run.
- 37. Copyright © 2004 South-Western/Thomson Learning Computing the Price Elasticity of Supply • The price elasticity of supply is computed as the percentage change in the quantity supplied divided by the percentage change in price. P r i c e e l a s t i c i t y o f s u p p l y = P e r c e n t a g e c h a n g e i n q u a n t i t y s u p p l i e d P e r c e n t a g e c h a n g e i n p r i c e
- 38. Copyright © 2004 South-Western/Thomson Learning APPLICATION of ELASTICITY • Can good news for farming be bad news for farmers? • What happens to wheat farmers and the market for wheat when university agronomists discover a new wheat hybrid that is more productive than existing varieties?
- 39. Copyright © 2004 South-Western/Thomson Learning THE APPLICATION OF SUPPLY, DEMAND, AND ELASTICITY • Examine whether the supply or demand curve shifts. • Determine the direction of the shift of the curve. • Use the supply-and-demand diagram to see how the market equilibrium changes.
- 40. Figure 8 An Increase in Supply in the Market for Wheat Copyright©2003 Southwestern/Thomson Learning Quantity of Wheat 0 Price of Wheat 3. . . . and a proportionately smaller increase in quantity sold. As a result, revenue falls from $300 to $220. Demand S1 S2 2. . . . leads to a large fall in price . . . 1. When demand is inelastic, an increase in supply . . . 2 110 $3 100
- 41. Copyright © 2004 South-Western/Thomson Learning Compute the Price Elasticity of Supply E D = − + − + = − ≈ − 1 0 0 1 1 0 1 0 0 1 1 0 2 3 0 0 2 0 0 3 0 0 2 0 0 2 0 0 9 5 0 4 0 2 4 ( ) / . . ( . . ) / . . . Supply is inelastic
- 42. Copyright © 2004 South-Western/Thomson Learning Summary • Price elasticity of demand measures how much the quantity demanded responds to changes in the price. • Price elasticity of demand is calculated as the percentage change in quantity demanded divided by the percentage change in price. • If a demand curve is elastic, total revenue falls when the price rises. • If it is inelastic, total revenue rises as the price rises.
- 43. Copyright © 2004 South-Western/Thomson Learning Summary • The income elasticity of demand measures how much the quantity demanded responds to changes in consumers’ income. • The cross-price elasticity of demand measures how much the quantity demanded of one good responds to the price of another good. • The price elasticity of supply measures how much the quantity supplied responds to changes in the price. .
- 44. Copyright © 2004 South-Western/Thomson Learning Summary • In most markets, supply is more elastic in the long run than in the short run. • The price elasticity of supply is calculated as the percentage change in quantity supplied divided by the percentage change in price. • The tools of supply and demand can be applied in many different types of markets.