Consumer Choice and Elasticity

Refer back to your Chapter 3 notes and mentally combine them with Chapter 7 notes

1) List the key factors influencing consumer behavior (repeat from Chapter 3 and on your own)
2) Apply the concept of marginal utility to determine how a demand curve is derived (repeat from
Chapter 3 and on your own)
3) Define, calculate, and graph elasticity of demand
4) Relate demand elasticity to total revenue
5) Define and calculate income elasticity
6) Define and graph elasticity of supply

Elasticity gives us more information about the consumer
Price elasticity seeks to quantify how much quantity demanded falls (rises)

Class Activity: Draw two demand curves side by side. Increase price by the same amount in each graph. Draw the first demand curve illustrating a small reduction in quantity demanded. Draw the second demand curve illustrating a large reduction in quantity demanded.

By how much does price need to rise to decrease quantity demanded by X%?
By how much does price need to fall to increase quantity demanded by Y%?

Price elasticity of demand= percentage change in quantity demanded / percentage change in price
Elasticity =

If ε > 1, then elastic
Consumers change their behavior a lot
If ε < 1, then inelastic
Consumers change their behavior a little
If ε = 1, then unitary elastic
Change in quantity demanded offsets change in price (total revenue stays the same)

Price elasticity is NOT the slope of the demand curve
– A straight-line demand curve will have constant slope but a different elasticity at every point

Class Activity: For each of the following goods, indicate whether you would be an elastic consumer (responsive to price changes), or an inelastic consumer
(unresponsive to price changes)
(1) Coffee
(2) Pizza
(3) Monthly cell phone fee
(4) Airfare

Three Clicker questions next

Q7.1 What year are you at FSU?
1) Freshman
2) Sophomore or higher

Q7.2 If FSU raised tuition by 5% for the next academic year, would you return to the
University?
1. Yes, I would return
2. No, I would transfer or drop out

Q7.3 If FSU raised tuition by 10% for the next academic year, would you return to the
University?
1. Yes, I would return
2. No, I would transfer or drop out

Class Activity: Economics is Everywhere
5.1

I often do a survey of my students to see if their demand for places at the university responds to prices. The price of places at the university is the tuition charged. I offer students the possibility of zero tuition increase for next year, a 5 percent increase for next year, and a 10 percent increase. Each student is then asked whether he or she will return next year. I recently got the following results: For a 5 percent tuition increase, the number of students returning would decrease by 2.2 percent, implying a price elasticity of demand equaling 0.44. For a 10 percent tuition increase, however, the number returning would fall by 11.8 percent, implying an elasticity of 1.18. The demand curve is surely downward sloping. Not only does the number of places demanded decline when tuition rises more; the responsiveness of demand- the price elasticity of demandis greater in percentage terms when the university tries to raise tuition by higher amounts. That’s not surprising: substitutes that suddenly become slightly cheaper don’t affect behavior proportionately as much as substitutes that suddenly become relatively a lot cheaper.
Q: Who is likely to be more inelastic, freshmen or juniors?
Why?

Two Clicker questions next

Q7.4 If a large percentage increase in the price of a good results in a small percentage reduction in the quantity demanded of the good, demand is said to be
1. unitary elastic.
2. relatively inelastic.
3. relatively elastic.
4. perfectly elastic.

Q7.5 Suppose the elasticity of demand is estimated to be 0.50. The firm is trying to increase sales by 15%. By how much does price need to change in order to achieve that goal?
1) Price needs to rise by 30%
2) Price needs to fall by 30%
3) Price needs to rise by 7.5%
4) Price needs to fall by 7.5%
5) Price needs to rise by 50%
6) Price needs to fall by 50%

(1) Availability of substitutes
– More substitutes, more elastic (more responsive)
(2) Share of budget
– Greater share, more elastic
(3) Time
– More time, more elastic

Clicker question next

Q7.6 Members of Alpha fraternity have developed a strong liking for Coca-Cola. Beta fraternity members buy the same amount of Coke but believe Pepsi is just about as good. From this, we can infer that
1.
Alpha members will not care what the price of Coke is.
2.
compared to Alpha members, Betas will have a smaller price elasticity of demand for Coke.
3.
compared to Alpha members, Betas will have a larger price elasticity of demand for Coke.
4.
Alpha members will increase their purchases by a larger amount of Pepsi than Beta members in response to a "50 cents off" sale on a case of Pepsi.

(1) Pair with a classmate
(2) One of you try to convince the other to raise prices
(3) One of you try to convince the other to lower prices

Clicker question next

Q7.7: The firm wants to increase revenue.
Should it raise or lower prices?
1. raise prices
2. lower prices

Q7.8: The firm wants to increase revenue.
Should it raise or lower prices?
1. raise prices
2. lower prices
3. it depends

Price elasticity of demand
Elastic
Unitary Elastic
Inelastic
Elasticity coefficient
(in absolute value)
1 to

1
0 to 1
Impact of higher price on total consumer expenditures or a firm’s total revenue decrease
-- unchanged-increase
Impact of lower price on total consumer expenditures or a firm’s total revenue increase
-- unchanged-decrease

Use it as a tool
Think about what elasticity tells us and then apply it to total revenue

Total Revenue (TR) to the firm is Total
Expenditure (TE) by the consumer.
TR = TE = P x Q
If elastic and price falls: ↓ P x
↑
Q = ↑TR
– Lower price and lots more is bought, Q dominates equation
If elastic and price rises: ↑ P x
↓
Q = ↓TR
– Raise price and lots less is bought, Q dominates equation

Total Revenue (TR) to the firm is Total
Expenditure (TE) by the consumer.
TR = TE = P x Q
If elastic and price falls: ↓ P x
↑
Q = ↑TR
– Lower price and lots more is bought, Q dominates equation
If elastic and price rises: ↑ P x
↓
Q = ↓TR
– Raise price and lots less is bought, Q dominates equation
If inelastic and price falls:
↓
P x ↑
Q = ↓TR
– Lower price and a little more is bought, P dominates equation
If inelastic and price rises:
↑
P x ↓
Q = ↑TR
– Raise price and a little less is bought, P dominates equation

4 graphs

Class Activity: Economics is Everywhere
5.5

The local airport in Austin, Texas, opened in 1999 with onsite parking, priced from $18 per day for garage parking to
$6 per day for distant uncovered parking. The lots were so crowded that soon the Airport Authority built an additional lot.
By 2002, off-site parking places had opened up, offering covered parking for $8 per day, and some offering threeminute shuttle service to the terminal. Not surprisingly, this entry of new competitors into the parking market has left many onsite places empty, and the airport’s parking revenues this year have fallen from $22 million to $18 million. If the Airport Authority is smart, it would think about what its demand elasticity is, lower prices if it believes demand is elastic, not lower them, and maybe even raise them (especially on garage parking) if it believes demand is inelastic. The evidence suggests management believes that the demand is elastic for the garage parking, because in
2004 they lowered the price for garage parking to $15 per day.
Q: For which part of the airport parking areas is the demand likely to be more or less elastic, the garage parking or the uncovered distant parking? In light of your beliefs about this question, how would you alter prices?

Three Clicker Questions next

Q7.9 Suppose ε = 0.52 and the firm raises price.
What happens to TR?
1. TR rises
2. TR falls
3. TR remains constant

Q7.10 Suppose the firm wants to raise TR and it knows demand is elastic. What should the firm do?
1. Lower price
2. Raise price
3. Keep price the same

Q7.11 (MA) In which of the following cases will the total spending on a good decrease?
1. Demand is elastic, and price decreases.
2. Demand is elastic, and price increases.
3. Demand is inelastic, and price increases.
4. Demand is inelastic, and price decreases.

Price elasticity measures the change in consumer purchases when price changes
Income elasticity measures the change in consumer purchases when

Price elasticity measures the change in consumer purchases when price changes
Income elasticity measures the change in consumer purchases when income changes
Income elasticity =

If positive, consumers buy more when income rises
Normal good - a good that consumers will buy more of when income rises
If negative, consumers buy less when income rises
Inferior good - a good that consumers will buy less of when income rises

Price elasticity of supply measures the responsiveness of quantity supplied to price changes
How much does quantity supplied increase (or decrease) when price rises
(or falls)?

1) List the key factors influencing consumer behavior (repeat from Chapter 3 and on your own)
2) Apply the concept of marginal utility to determine how a demand curve is derived (repeat from
Chapter 3 and on your own)
3) Define, calculate, and graph elasticity of demand
4) Relate demand elasticity to total revenue
5) Define and calculate income elasticity
6) Define and graph elasticity of supply