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Elasticities of Demand and Supply 1
ELASTICITIES OF DEMAND AND SUPPLY
ECO 2023Principles of Microeconomics
Dr. McCaleb
Elasticities of Demand and Supply 2
TOPIC OUTLINE
I. Price Elasticity of Demand
II. Application: Elasticity and the Demand for Smoking
III. Price Elasticity of Supply
IV. Cross Price Elasticity and Income Elasticity
Elasticities of Demand and Supply 3
Price Elasticity of Demand
Elasticities of Demand and Supply 4
PRICE ELASTICITY OF DEMAND
What Is the Price Elasticity of Demand?
The price elasticity of demand is the ratio of the percentage change in the quantity demanded to the percentage change in price.
Price elasticity ofdemand
Percent change in quantity demanded
Percent change in price=
What Is the Price Elasticity of Demand Used For?
It measures the size of the change in quantity demanded when the price of a good changes.
Elasticities of Demand and Supply 5
PRICE ELASTICITY OF DEMAND
How Is the Price Elasticity of Demand Calculated?
Mid-point method
Calculate the change in quantity demanded as a percent of the average of the two quantities and multiply by 100 to convert to percent
x 100Percent change
in quantity
New quantity – Initial quantity
(New quantity + Initial quantity) ÷ 2=
Elasticities of Demand and Supply 6
PRICE ELASTICITY OF DEMAND
How Is the Price Elasticity of Demand Calculated?
Calculate the change in price as a percent of the average of the two prices and multiply by 100 to convert to percent
x 100Percent change in price =New price – Initial price
(New Price + Initial Price) ÷ 2
Elasticities of Demand and Supply 7
PRICE ELASTICITY OF DEMAND
Why Do Economists Use Elasticity to Measure the Size of the Change?
Because elasticity is a ratio of two percentages, the percentages “cancel out” so that elasticity is a pure number, a number with no units of measurement attached to it.
That allows us to compare the demands for different goods even though they are measured in different units or to compare goods at different points in time or even to compare goods in different countries that use different currencies.
Elasticities of Demand and Supply 8
The quantity demanded of lattes at a Starbucks decreases from 15 cups per hour to 5 cups per hour when the price increases from $3.00 to $5.00. Using the mid-point method, what is the percent change in quantity demanded? (Hint: Make sure the answer is in percent. Include the negative sign if it is negative, but do not include the percent sign.)
Elasticities of Demand and Supply 9
The quantity demanded of lattes at a Starbucks decreases from 15 cups per hour to 5 cups per hour when the price increases from $3.00 to $5.00. Using the mid-point method, what is the percent change in price? (Hint: Make sure the answer is in percent. Include the negative sign if it is negative, but do not include the percent sign.)
Elasticities of Demand and Supply 10
The quantity demanded of lattes at a Starbucks decreases from 15 cups per hour to 5 cups per hour when the price increases from $3.00 to $5.00. What is the elasticity of demand? (Hint: No decimal numbers. If the answer is negative, include the negative sign.)
Elasticities of Demand and Supply 11
PRICE ELASTICITY OF DEMAND
What Does the Elasticity Number or Coefficient Mean?
The absolute value of the elasticity coefficient shows whether the quantity change is bigger than the price change, the same size as the price change, or smaller than the price change.
The bigger the absolute value, the more sensitive or responsive consumers are to a price change.
The smaller the absolute value, the less sensitive or responsive they are to a price change.
Elasticities of Demand and Supply 12
PRICE ELASTICITY OF DEMAND
What Does an Elasticity Coefficient Greater than 1 in Absolute Value Mean?
Demand is elastic.
The percent change in quantity demanded is greater than the percent change in price
Consumers are relatively sensitive or responsive to price changes.
Elasticities of Demand and Supply 13
PRICE ELASTICITY OF DEMAND
What Does an Elasticity Coefficient Smaller than 1 in Absolute Value Mean?
Demand is inelastic.
The percent change in quantity demanded is smaller than the percent change in price
Consumers are relatively insensitive or not very responsive to price changes.
Elasticities of Demand and Supply 14
PRICE ELASTICITY OF DEMAND
What Does an Elasticity Coefficient Equal to 1 in Absolute Value Mean?
Demand is unit elastic.
The percent change in quantity demanded equals the percent change in price
Consumers are neither very sensitive or responsive to price changes nor are they very insensitive or unresponsive.
Elasticities of Demand and Supply 15
PRICE ELASTICITY OF DEMAND
What Does It Mean When the Elasticity Coefficient Is Equal to 0?
Demand is perfectly inelastic.
The percentage change in quantity demanded is zero when the price changes.
Consumers are completely insensitive or unresponsive to the price change. They want the same quantity no matter what the price is.
A perfectly inelastic demand curve is vertical.
Elasticities of Demand and Supply 16
PRICE ELASTICITY OF DEMAND
When the price rises, . . . the quantity demanded does not change.
There is no change in the quantity demanded when price changes. Therefore, demand is perfectly inelastic.
Special Case: Perfectly Inelastic Demand
Elasticities of Demand and Supply 17
PRICE ELASTICITY OF DEMAND
What Does It Mean If the Elasticity Coefficient Is Infinite?
Demand is perfectly elastic.
Even an infinitesimally small percentage price change will cause a very (“infinitely”) large percentage change in quantity demanded.
The numerator (the percent change in quantity demanded) is so large and the denominator (the percent change in price) is so small that the coefficient of elasticity approaches infinity in the limit.
The demand curve is horizontal are almost so.
Elasticities of Demand and Supply 18
PRICE ELASTICITY OF DEMAND
For even a very small change in the price of spring water, . . . the quantity demanded of spring water changes by a very large amount.
The change in the quantity demanded is much (infinitely) larger than the change in price. Therefore, the demand for spring water is perfectly elastic.
Special Case: Perfectly Elastic Demand
Elasticities of Demand and Supply 19
If the price elasticity of demand for furniture is 1.26, the demand for furniture is
1. Perfectly elastic
2. Elastic but not perfectly elastic
3. Unit elastic
4. Inelastic but not perfectly inelastic
5. Perfectly inelastic
Elasticities of Demand and Supply 20
If the price elasticity of demand for furniture is 1.26, the percent change in quantity demanded is _____ the percent change in price and buyers are _____ sensitive to price changes.
1. Greater than; very
2. Greater than; not very
3. Less than; very
4. Less than; not very
Elasticities of Demand and Supply 21
If the price elasticity of demand for tobacco is 0.61, the demand for tobacco is
1. Perfectly elastic
2. Elastic but not perfectly elastic
3. Unit elastic
4. Inelastic but not perfectly inelastic
5. Perfectly inelastic
Elasticities of Demand and Supply 22
If the price elasticity of demand for tobacco is 0.61, the percent change in quantity demanded is _____ the percent change in price and buyers are _____ sensitive to price changes.
1. Greater than; very
2. Greater than; not very
3. Less than; very
4. Less than; not very
Elasticities of Demand and Supply 23
PRICE ELASTICITY OF DEMAND
What Causes the Demand for Some Goods To Be More Elastic or More Inelastic than Others?
• Substitution effects
• Income effects
• Time
Elasticities of Demand and Supply 24
PRICE ELASTICITY OF DEMAND
Substitution effects
If it is easy to find a substitute for a good, then, ceteris paribus, the demand for the good tends to be more elastic or less inelastic.
More or better substitutes Higher elasticity
If it is harder to find a substitute for a good, then, ceteris paribus, the demand for the good tends to be more inelastic or less elastic.
Few or poorer substitutes Lower elasticity
Elasticities of Demand and Supply 25
PRICE ELASTICITY OF DEMAND
Substitution effects: Examples
• Ceteris paribus, the demand for Toyota Camrys is likely to be more elastic (or less inelastic) than the demand for automobiles which in turn is more elastic (or less inelastic) than the demand for motor vehicles.
• The demand for a college textbook is likely to be more inelastic (or less elastic), ceteris paribus, than the demand for a popular novel.
Elasticities of Demand and Supply 26
PRICE ELASTICITY OF DEMAND
Income Effects
If consumers spend a relatively larger percent of their income on a good, then, ceteris paribus, the demand for the good tends to be more elastic or less inelastic.
Larger share of income Higher elasticity
If consumers spend a relatively smaller percent of their income on a good, then, ceteris paribus, the demand for the good tends to be less elastic or more inelastic.
Smaller share of income Lower elasticity
Elasticities of Demand and Supply 27
PRICE ELASTICITY OF DEMAND
Income Effects: Examples
• Purchases of automobiles require a larger proportion of income than purchases of gasoline so, ceteris paribus, the demand for automobiles is likely to be more elastic (or less inelastic) than the demand for gasoline.
• Households spend more of their income on steak than on the salt to put on the steak. Ceteris paribus, the demand salt is likely to be more inelastic (or less elastic) than the demand for steak.
Elasticities of Demand and Supply 28
PRICE ELASTICITY OF DEMAND
Time
The longer the time period over which elasticity is measured, the larger, ceteris paribus, it is likely to be because consumers have more time to find good substitutes and adjust their consumption.
Longer time Higher elasticity
Shorter time Lower elasticity
Example: The elasticity of demand for gasoline is very low one day or one week after a change in the price, but the elasticity is higher (although still inelastic) one year after the price change. In fact, the demand for gasoline becomes elastic after several years have passed.
Elasticities of Demand and Supply 29
Universal to cut price of CD's to raise salesAmy Harmon New York Times
Friday, September 5, 2003
Universal Music Group's plan to cut prices on compact discs by as much as 30 percent represents a big gamble in its aggressive bid to lure consumers back into record stores.
The deep price cut, announced on Wednesday, is the only one to apply to new CD's since the format was introduced in the early 1980's.
Universal, owned by Vivendi Universal, is betting that consumers will buy more CD's once the price dips below $13.
Elasticities of Demand and Supply 30
PRICE ELASTICITY OF DEMAND
Total Revenue and Price Elasticity of Demand
Relationship between price elasticity of demand and total revenue
There is a unique relationship between the price elasticity of demand, a change in the price of the good, and sellers’ total revenue from (or buyers’ total expenditure on) the good.
This relationship is valid for the price elasticity of demand only. It is not valid for any other elasticity (that is, income elasticity of demand, price elasticity of supply, or cross-elasticities).
Elasticities of Demand and Supply 31
PRICE ELASTICITY OF DEMAND
Total Revenue and Price Elasticity of Demand
Elastic demand
• If demand is elastic, a price change results in a change in total revenue (or total expenditure) in the opposite direction.
P increase TR decreaseP decrease TR increase
• According to the law of demand, a price change causes a change in quantity demanded in the opposite direction. Because demand is elastic, the quantity change is bigger than the price change. So the quantity change determines what happens to total revenue.
Elasticities of Demand and Supply 32
PRICE ELASTICITY OF DEMAND Total Revenue and Price Elasticity of Demand
Inelastic demand
• If demand is inelastic, a price change results in a change in total revenue (or total expenditure) in the same direction.
P increase TR increaseP decrease TR decrease
• According to the law of demand, a price change causes a change in quantity demanded in the opposite direction. Because demand is inelastic, the price change is bigger than the quantity change. So the price change determines what happens to total revenue.
Elasticities of Demand and Supply 33
PRICE ELASTICITY OF DEMAND Total Revenue and Price Elasticity of Demand
Unit elastic demand
• If demand is unit elastic, a price change results in no change in total revenue (or total expenditure).
P increase TR unchangedP decrease TR unchanged
• According to the law of demand, a price change causes a change in quantity demanded in the opposite direction. Because demand is unit elastic, the quantity change equals the price change. So the quantity change and the price change offset each other and total revenue doesn’t change.
Elasticities of Demand and Supply 34
The price elasticity of demand for automobiles is 1.35. If Toyota wants to increase its revenues, it should
1. Raise price
2. Leave price unchanged
3. Lower price
Elasticities of Demand and Supply 35
President Weatherell wants to raise tuition (price) by a significant amount to increase the University's budget (total revenue). Therefore, he must be assuming that your demand for an FSU education is
1. elastic
2. unit elastic
3. inelastic
Elasticities of Demand and Supply 36
The demand for most agricultural commodities is inelastic. Therefore, when a freeze reduces the size of the orange crop, total revenue of all orange growers increases even though the incomes of growers who lose a large part of their crop falls.
Elasticities of Demand and Supply 37
Application: Elasticity and the Demand for Smoking
Elasticities of Demand and Supply 38
ELASTICITY AND THE DEMAND FOR SMOKING
Example: Oregon’s Anti-Smoking Campaign
In November 1996, residents of Oregon approved a ballot measure increasing the excise tax on sellers of cigarettes by $0.30 per pack.
The average price per pack increased from $1.75 to $2.05.
Annual per capita consumption decreased from 92 packs to 86 packs.
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Elasticities of Demand and Supply 39
ELASTICITY AND THE DEMAND FOR SMOKING
Example: Oregon’s Anti-Smoking Campaign
10% of the additional tax revenue was allocated to the Oregon Health Division (OHD) to develop and implement a tobacco-use prevention program.
Because of the fall in demand, annual per capita consumption decreased by an additional 4 packs, from 86 to 82.
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Elasticities of Demand and Supply 40
Addiction and Elasticity
Nonusers
Nonusers’ demand for addictive substances is elastic. For example, the estimated elasticity of demand for cigarettes among teenage nonusers is 1.2.
Therefore, a moderately higher price leads to a substantially smaller number of people trying a drug.
ELASTICITY AND THE DEMAND FOR SMOKING
Elasticities of Demand and Supply 41
Addiction and Elasticity
Users
Existing users’ demand for addictive substances is inelastic. For example, the estimated elasticity of demand for cigarettes among adult smokers is 0.4.
Therefore, a substantial price rise brings only a modest decrease in the quantity demanded. Even addicted users, however, may reduce their consumption at the margin so demand is not perfectly inelastic.
ELASTICITY AND THE DEMAND FOR SMOKING
Elasticities of Demand and Supply 42
Price Elasticity of Supply
Elasticities of Demand and Supply 43
PRICE ELASTICITY OF SUPPLY
What Is the Price Elasticity of Supply?
The price elasticity of supply is the ratio of the percent change in the quantity supplied to the percent change in price.
Price elasticity ofsupply
Percentage change in quantity supplied
Percentage change in price=
The price elasticity of supply is interpreted in the same way as the price elasticity of demand.
Elasticities of Demand and Supply 44
PRICE ELASTICITY OF SUPPLY
• What Causes the Supply of Some Goods To Be More Elastic or More Inelastic than Others?
• Substitution effects
• Time: Same effect as elasticity of demand
Elasticities of Demand and Supply 45
PRICE ELASTICITY OF SUPPLY
Substitution effects
If it is easy for sellers to switch production and sales to another good, if they have good alternative uses for their productive inputs, then, ceteris paribus, the supply of the good tends to be more elastic or less inelastic.
More or better substitutes Higher elasticity
If it is harder for sellers to switch to production and sales of alternative goods, if inputs tend to be more specialized, then, ceteris paribus, the supply of the good tends to be more inelastic or less elastic.
Few or poorer substitutes Lower elasticity
Elasticities of Demand and Supply 46
PRICE ELASTICITY OF DEMAND
Substitution effects: Examples
• Ceteris paribus, the supply of physicians is likely to be more elastic (or less inelastic) than the supply of surgeons which in turn is more elastic (or less inelastic) than the supply of neurosurgeons. The more specialized the resources required to produce a good, the less elastic its supply is likely to be.
• Storage provides sellers with a way of substituting between current sales and future sales. Ceteris paribus, the lower the cost of storing a good, frozen fish for example, the more elastic is its supply. On the other hand, the supply of a non-storable good like fresh fish is highly inelastic.
Elasticities of Demand and Supply 47
Cross Price Elasticity and Income Elasticity of Demand
Elasticities of Demand and Supply 48
CROSS PRICE ELASTICITY AND INCOME ELASTICITY OF DEMAND
What Is the Cross Price Elasticity of Demand?
Cross elasticityof demand
Percent change in quantity demanded of agood
Percent change in the price of one of itssubstitutes or complements
=
The ratio of the percent change in quantity demanded of a good to the percent change in the price of a substitute or a complement.
Elasticities of Demand and Supply 49
CROSS ELASTICITY AND INCOME ELASTICITY OF DEMAND
Substitutes
Suppose that when the price of a burger falls by 10 percent, the quantity of pizza demanded decreases by 5 percent.
Cross elasticity ofdemand for pizza
– 5 percent
– 10 percent= = 0.5
The cross price elasticity of demand between substitutes is positive.
Elasticities of Demand and Supply 50
CROSS ELASTICITY AND INCOME ELASTICITY OF DEMAND
Complements
Suppose that when the price of a burger falls by 10 percent, the quantity of pizza demanded decreases by 5 percent.
The cross price elasticity of demand between complements is negative.
Cross elasticity ofdemand for pizza
2 percent
– 10 percent= = -0.2
Elasticities of Demand and Supply 51
What Is the Income Elasticity of Demand?
The ratio of the percent change in quantity demanded to the percent change in buyers’ incomes.
CROSS ELASTICITY AND INCOME ELASTICITY OF DEMAND
Income elasticityof demand
Percentage change in quantity demanded
Percentage change in income=
Positive income elasticity normal good
Negative income elasticity inferior good
Elasticities of Demand and Supply 52
If the cross price elasticity of demand between two goods is positive, the two goods are
1. Normal
2. Inferior
3. Substitutes
4. Complements
5. Elastic
6. inelastic
Elasticities of Demand and Supply 53
If the cross price elasticity of demand between two goods is negative, the two goods are
1. Normal
2. Inferior
3. Substitutes
4. Complements
5. Elastic
6. inelastic
Elasticities of Demand and Supply 54
True or false: If the income elasticity of demand for a good is positive and less than 1 in absolute value, the good is a normal good and the demand for the good is inelastic.
Elasticities of Demand and Supply 55
True or false: If the income elasticity of demand for a good is negative and greater than 1 in absolute value, the good is an inferior good and the demand for the good is elastic.