demand curves. do you own an ipod? 1)yes 2)no clicker test press the letter a on your clicker
Post on 19-Dec-2015
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What is the most you would be willing to pay for an iPod Nano? (if you didn’t have an iPod and couldn’t
get one for less)
1) Less than $1002) $101-$1503) $151-$2004) $201-$2505) $251-$3006) $301-$3507) $351-$4008) $401-$5009) $501-$60010)More than $600
What is the most you would be willing to pay for an iPhone? (if you couldn’t get one for less)
1) Less than $1002) $101-$2003) $201-$3004) $301-$4005) $401-$5006) $501-$6007) $601-$7008) $701-$8009) $801-$100010)More than $1000
Price and Quantity
• Apple recently announced that it had sold a total of 1 million iPhones.
• Price was $599 when introduced in July, 2007.• In September, 2007 Apple cut the price to
$399.• How will this affect Apple sales?
Demand function
• The demand function for a good reports the number of units that demanders will want to buy as a function of the price of the good.– Individual demand function: Number of units one
person will buy as function of price.– Market demand: Total number of units bought as
a function of price.
Drawing demand curve
• Economics tradition: Put quantity on horizontal axis, price on vertical axis.
• Typically demand curve slopes down: Higher price means lower quantity demanded.
Quantity
Price
Individual demand: reservation price model
• Consider a good, like an iPod, or a refrigerator, or a textbook, such that most demanders buy one unit or none at all.(A second unit isn’t of much use.)
• A demander’s “reservation price” or “Buyer Value” is the highest price that he would be willing to pay to have the good rather than not have it.
• Answers to our iPod and iPhone questions are Buyer Values.
A Market demand CurveBuyer Value Number of
Demanders
$100 10
$200 15
$300 10
$300
$100
$200
10 25 35
Price
Quantity
If price is $10, how many units will be demanded?
Buyer Value # Demanders
$20 11
$40 21
A) 0 unitsB) 11 unitsC) 21 unitsD) 32 units
If price is $30, how many units will be demanded?
Buyer Value # Demanders
$20 11
$40 21
A) 0 unitsB) 11 unitsC) 21 unitsD) 32 units
Many consumers, many steps
• The market demand curve in our example had only 3 different Buyer Values and hence was like a stairway with 3 steps.
• If there are many demanders with different Buyer Values, steps become small, demand curve is well approximated by a continuous curve.
Linear demand curve
• A useful example: Linear demand curve.• p=a-bq for some a and b.
• Total expenditures on a Good are price x quantity.Note that pq=(a-bq)q=aq-bq2
Quantity
Price
Individuals may consume more than one unit.
• Typical case: Diminishing marginal willingness to pay for an additional unit.
• Keep buying so long as one more unit is worth more than the price.
• This implies that you will buy more units if price is lower.
Individual demand for gasoline
• The higher the price of gasoline, the less gasoline per month someone will buy.
Price pergallon
Gallons Per month
Market demand
• For any price, market demand is sum of quantities demanded by individuals.
Person 1Demand Curve
Person 2Demand Curve
Market demandCurve
Price
Consumers’ Surplus
• Difference between what you pay for a good and the most you would be willing to pay rather than go without the good.
• Example: You are willing to pay $350 for an IPOD nano. They cost $199.
• What is your consumers’ surplus?
Consumers’ surplus for consumer who demands multiple goods.
• Area under demand curve, above the price.
Consumer’sSurplus
Readings
• Prepare for Experiment 1 by reading description of this experiment in Bergstrom Miller text.
• Show up at your section. You must go to your own section.
• Read McAfee, Chapter 2, Section 2.1.1.(If you don’t know calculus, skip the calculus
discussion on pp 2-11-2-14.)
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