# Price Elasticities of Demand

## Presentation on theme: "Price Elasticities of Demand"— Presentation transcript:

Price Elasticities of Demand

Definition: Price elasticity of demand is a measure of the responsiveness of the quantity demanded of a good to a change in its price when all other influences on buyers’ plans remain the same To determine price elasticity of demand: compare the % change in the quantity demanded with the percentage change in price

Percentage Price in Change
Starbucks raised the price of a latte from \$3 to \$5 a cup. What is the percentage change in price? Percent change in price = New price – Initial price Initial Price x 100

Percentage Change in Price
Starbucks cuts the price of a latte from \$5 to \$3 a cup. What now is the percentage change in price? Percent change in price = New price – Initial price Initial Price x 100

Percentage Change in Price
Elasticity compares the percentage change in the quantity demanded with the percentage change in price Midpoint Method -- To calculate the percentage change that does not depend on the direction of the price change

Percentage Price in Change
Midpoint Method Calculation Starbucks Latte price changing from \$5 to \$3. \$5 for a new price and \$3 for the initial price. x 100 Percent change in price = New price – Initial price (New Price + Initial Price) ÷ 2

Percentage Change in Price
Average price is the same regardless of whether the price rises or falls

Percentage Change in Quantity Demanded
Price of a Latte rises from \$3 to \$5 a cup, the quantity demanded decreases from 15 cups to 5 cups an hour. Uses the midpoint formula again x 100 Percent change in price = New price – Initial price (New Price + Initial Price) ÷ 2

Percentage Change in Quantity Demanded
When the price of a good rises, the quantity demanded of it decreases A positive change in price bring a negative change in the quantity demanded When the price of a good falls, the quantity demanded of it increases Negative change in price brings a positive change in the quantity demanded

Elastic and Inelastic Demand
Elastic Demand – when the percentage change in the quantity demanded exceeds the percentage change in price Unit Elastic Demand – percentage change in the quantity demanded equals the percentage change in price Inelastic Demand – percentage change in the quantity demanded is less than the percentage change in price

Elastic Demand Perfectly Elastic Demand – an almost zero percentage change in the price brings a very large percentage change in the quantity demanded Consumers are willing to buy any quantity of the good at a given price but none at a higher price

Perfectly Elastic Demand

Elastic Demand A percentage change in the quantity demanded exceeds the percentage change in price

Unit Elastic Demand The percentage change in the quantity demanded equals the percentage change in price

Inelastic Demand Percentage change in the quantity demanded is less than the percentage change in price

Perfectly Inelastic Demand
Percentage change in the quantity demanded is zero for any percentage change in price

Influences on Price Elasticity of Demand
Two influences: Availability of substitutes Proportion of income spent

Influences on Price Elasticity of Demand
Demand for good is elastic if a substitute is easy to find Soft drink containers Demand for good is inelastic if a substitute is hard to find Oil substitutes?

Influences on Price Elasticity of Demand
Three factors that influence the ability to find a substitute for a good: Whether good is a luxury or a necessity How narrowly it is defined Amount of time available to find a substitute for it

Price Elasticity of Demand
The greater the proportion of income spend on a good, the greater is the impact of a rise in its price on the quantity of that good that people can afford to buy and the more elastic it is the demand for that good Toothpaste?

Computing Price Elasticity of Demand
Percentage change in quantity demanded Percentage change in the price = If the price elasticity of a demand is greater than 1, the demand is elastic If the price elasticity of demand equals 1, demand is unit elastic If the price elasticity of demand is less than 1, demand is inelastic

Computing Price Elasticity of Demand

Elasticity Along a Linear Demand Curve
Slope measures responsiveness. But slope and elasticity are not the same thing! Along a linear (straight-line) demand curve, the slope is constant but the elasticity varies. Along a linear demand curve, demand is: Unit elastic at the midpoint of the curve. Elastic above the midpoint of the curve. Inelastic below the midpoint of the curve.

Elasticity Along a Linear Demand Curve

Total Revenue and the Price Elasticity of Demand
Total revenue is the amount spent on a good and received by its sellers and equals the price of the good multiplied by the quantity sold Starbucks Latte -- \$3 Demand is 15 cups an hour Total Revenue is \$45 an hour Total Revenue Test is a method of estimating the price elasticity of demand by observing the change in total revenue that results from a price change

Total Revenue and the Price Elasticity of Demand
If demand is elastic: A given percentage rise in price brings a larger percentage decrease in the quantity demanded. And total revenue decreases. If demand is inelastic: A given percentage rise in price brings a smaller percentage decrease in the quantity demanded. And total revenue increases.

Total Revenue Test Total revenue test:
If price and total revenue change in the opposite directions, demand is elastic. If a price change leaves total revenue unchanged, demand is unit elastic. If price and total revenue change in the same direction, demand is inelastic.

Total Revenue Test At \$3 a cup, the quantity demanded is 15 cups an hour. Total revenue is \$45 an hour. When the price rises to \$5 a cup, the quantity demanded decreases to 5 cups an hour. Total revenue decreases to \$25 an hour. Demand is elastic.

Total Revenue Test At \$50 a book, the quantity demanded is 5 million books. Total revenue is \$250 million. When the price rises to \$75 a book, the quantity demanded decreases to 4 million books. Total revenue increases to \$300 million. Demand is inelastic. Total revenue is \$250 million.

Nonusers’ demand for addictive substances is elastic. So a moderately higher price leads to a substantially smaller number of people trying a drug. Existing users’ demand for addictive substances is inelastic. So even a substantial price rise brings only a modest decrease in the quantity demanded.

Price Elasticities of Demand Notes

Definition: Price elasticity of demand is
To determine price elasticity of demand: compare the % change in the quantity demanded with the percentage change in price

Percentage Price in Change
Starbucks raised the price of a latte from \$3 to \$5 a cup. What is the percentage change in price? = x

Percentage Change in Price
Starbucks cuts the price of a latte from \$5 to \$3 a cup. What now is the percentage change in price? = x

Percentage Change in Price
Elasticity compares the percentage change in the quantity demanded with the percentage change in price Midpoint Method --

Percentage Price in Change
Midpoint Method Calculation Starbucks Latte price changing from \$5 to \$3. \$5 for a new price and \$3 for the initial price. x = ( ) ÷ 2

Percentage Change in Price

Percentage Change in Quantity Demanded
Price of a Latte rises from \$3 to \$5 a cup, the quantity demanded decreases from 15 cups to 5 cups an hour. Uses the midpoint formula again x 100 Percent change in price = New price – Initial price (New Price + Initial Price) ÷ 2

Percentage Change in Quantity Demanded
When the price of a good rises, the quantity demanded of it decreases When the price of a good falls, the quantity demanded of it increases

Elastic and Inelastic Demand
Unit Elastic Demand – Inelastic Demand –

Elastic Demand Perfectly Elastic Demand –
Consumers are willing to buy any quantity of the good at a given price but none at a higher price

Perfectly Elastic Demand

Elastic Demand

Unit Elastic Demand

Inelastic Demand

Perfectly Inelastic Demand

Influences on Price Elasticity of Demand
Two influences: Availability of ________________ Proportion of ___________spent

Influences on Price Elasticity of Demand
Demand for good is elastic if a substitute is easy to find Demand for good is inelastic if a substitute is hard to find

Influences on Price Elasticity of Demand
Three factors that influence the ability to find a substitute for a good:

Price Elasticity of Demand
The greater the proportion of income spend on a good, the greater is the impact of a rise in its price on the quantity of that good that people can afford to buy and the more elastic it is the demand for that good

Computing Price Elasticity of Demand
Percentage change in quantity demanded Percentage change in the price = If the price elasticity of a demand is greater than 1, the demand is ____________ If the price elasticity of demand equals 1, demand is ____________ If the price elasticity of demand is less than 1, demand is ____________

Computing Price Elasticity of Demand

Elasticity Along a Linear Demand Curve
Slope measures responsiveness. But slope and elasticity are not the same thing! Along a linear (straight-line) demand curve, the slope is constant but the elasticity varies. Along a linear demand curve, demand is: ____________ at the midpoint of the curve. ____________ above the midpoint of the curve. ____________ below the midpoint of the curve.

Elasticity Along a Linear Demand Curve

Total Revenue and the Price Elasticity of Demand
Total revenue is the amount spent on a good and received by its sellers and equals the price of the good multiplied by the quantity sold Starbucks Latte -- \$3 Demand is 15 cups an hour Total Revenue is \$45 an hour Total Revenue Test is a method of estimating the price elasticity of demand by observing the change in total revenue that results from a price change

Total Revenue and the Price Elasticity of Demand
If demand is elastic: If demand is inelastic:

Total Revenue Test Total revenue test:
If price and total revenue change in the opposite directions, demand is ________ If a price change leaves total revenue unchanged, demand is ____________. If price and total revenue change in the same direction, demand is ____________.

Total Revenue Test At \$3 a cup, the quantity demanded is 15 cups an hour. Total revenue is ____________ When the price rises to \$5 a cup, the quantity demanded decreases to 5 cups an hour. Total revenue decreases to ____________. Demand is ____________.

Total Revenue Test At \$50 a book, the quantity demanded is 5 million books. Total revenue is ____________ When the price rises to \$75 a book, the quantity demanded decreases to 4 million books. Total revenue increases to ____________. Demand is ____________. Total revenue is \$250 million.