Principle of Economicshomepage.ntu.edu.tw/~elliottfan/1020/slides/Lecture3.pdf · Principle of...
Transcript of Principle of Economicshomepage.ntu.edu.tw/~elliottfan/1020/slides/Lecture3.pdf · Principle of...
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ECO1020Principle of Economics
ECO1020 2020 Fall1
Chapter 4Demand, Supply, and
Equilibrium
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Chapter Outline
4.1 Markets4.2 How Do Buyers Behave?4.3 How Do Sellers Behave?4.4 Supply and Demand in Equilibrium4.5 What Would Happen if the Government Tried to
Dictate the Price of Gasoline?
4 Demand, Supply, and Equilibrium
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Why do brown eggs cost more than white eggs?
4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
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4.1 Markets
The market price is the price at which buyers and sellers conduct transactions.
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4.2 How Do Buyers Behave?
Quantity DemandedThe amount of a good that buyers are willing to purchase at a given price.
Demand ScheduleA table that reports the quantity demanded at different prices, holding all else equal.
Demand CurvePlots the quantity demanded at different prices.
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Exhibit 4.1 Chloe’s Demand Schedule and Demand Curve for Gasoline
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4.2 How Do Buyers Behave?
Quiz:
Using data from the previous slide, show the inverse‐demand function, that is, price as a function of quantity demanded (gallons per day).
Hint: the format of the function should look like:
Where G and P refer to gallons and oil price, respectively.
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4.2 How Do Buyers Behave?
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Note that:
• a refers to the intercept in the graph. Namely, the corresponding price when
• b refers to the slope of the line
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4.2 How Do Buyers Behave?
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Note, you can transform the inverse‐demand function to be the demand function:
Which indicates that quantity demanded is a function of price.
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Exhibit 4.2 Aggregation of Demand Schedules and Demand Curves
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4.2 How Do Buyers Behave?
More quizzes (your Assignment 2):
1. Derive the inverse‐demand function for Sue
2. Derive the inverse‐demand function for Carlos
3. Derive the inverse‐demand function for the entire market
4. Can you obtain 3 directly from 1 and 2?
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4.2 How Do Buyers Behave?
How much would you be willing to pay for a cone of ice cream?
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How much are you willing to pay for an “A”?
$15.00
$35.00
$55.00
$75.00
$95.00
$115.00
$135.00
$155.00
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Price
Quantity
Demand Curve for ice cream Demand Schedule
Price Quantity Demanded
$20 20
$30 16
$50 12
$100 7
$150 2
4.2 How Do Buyers Behave?
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4.2 How Do Buyers Behave?Willingness to Pay
Why are some students willing to pay more for ice cream than others? That is, why isn’t the price the same for everyone?
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I would pay EVERYTHING for this.
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4.2 How Do Buyers Behave?From Individual Demand Curves to Aggregated Demand Curves
Market Demand CurveThe sum of the individual demand curves of all the potential buyers. The market demand curve plots the relationship between the total quantity demanded and the market price, holding all else equal.
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4.2 How Do Buyers Behave?From Individual Demand Curves to Aggregated Demand Curves
Market Demand for ice cream
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Remember your willingness to pay for ice cream?
What if the weather turns very cold today?
Would you be willing to pay more or less than before?
4.2 How Do Buyers Behave?Shifting the Demand Curve
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4.2 How Do Buyers Behave?Shifting the Demand Curve
Shifts of the Demand Curveoccur when one of the following changes:
1. tastes and preferences2. income and wealth3. availability and prices of related goods4. number and scale of buyers5. buyers’ expectations about the future
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$15.00
$35.00
$55.00
$75.00
$95.00
$115.00
$135.00
$155.00
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Price
Quantity
Demand Curve for ice creamDemand Schedule
Price Quantity Demanded
$20 20
$30 16
$50 12
$100 7
$150 2
$15.00
$35.00
$55.00
$75.00
$95.00
$115.00
$135.00
$155.00
0 5 10 15 20
Demand for ice cream Demand Schedule
Price Quantity Demanded
$20 10
$30 8
$50 5
$100 2
$150 0
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4.2 How Do Buyers Behave?Shifting the Demand Curve
Exhibit 4.4 Shifts of the Demand Curve vs. Movement Along the Demand CurveECO1020 2020 Fall
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4.2 How Do Buyers Behave?Shifting the Demand Curve
Exhibit 4.3 Market Demand Curve for Oil
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4 What Would Happen If the Government Tried to Dictate the Price of Gasoline
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Evidence‐Based Economics Example:
How much more gasoline would people buy if its price were lower?
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4 What Would Happen If the Government Tried to Dictate the Price of Gasoline
Exhibit 4.5 The Quantity of Gasoline Demanded (per person) and the Price of Gasoline in Brazil, Mexico, and Venezuela
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4.3 How Do Sellers Behave?
How much would you have to be paid to sing a song in class?
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4.3 How Do Sellers Behave?
Quantity SuppliedThe amount of a good that sellers are willing to sell at a given price.
Supply ScheduleA table that reports the quantity supplied at different prices.
Supply CurvePlots the quantity supplied at different prices.
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4.3 How Do Sellers Behave?
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Supply curve for in‐class singing
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4.3 How Do Sellers Behave?
Why are more of you willing to sing in class, the higher the price?
Why is the price not the same for everybody?
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4.3 How Do Sellers Behave?
Market Supply CurvePlots the relationship between the total quantity supplied and the market price, holding all else equal.
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4.3 How Do Sellers Behave?From the Individual Supply to the Market Supply Curve
Market Supply for Classroom Singing
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4.3 How Do Sellers Behave?From the Individual Supply Curve to the Market Supply Curve
Remember what price you required to sing in class?
What if you were at a Karaoke party?
Would you require more or less to take off your clothes at the beach?
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4.3 How Do Sellers Behave?Shifting the Supply Curve
Shifts of the Supply Curve
Occur when one of the following changes:
1. input prices 2. technology3. number and scale of sellers4. sellers’ expectations about the future
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4.3 How Do Sellers Behave?Shifting the Supply Curve
Shift of Supply Curve for In‐class Singing
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4.3 How Do Sellers Behave?Shifting the Supply Curve
Exhibit 4.8 Market Supply Curve for Oil
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4.4 Supply and Demand in Equilibrium
Competitive EquilibriumThe point at which the market comes to an agreement about what the price will be (competitive equilibrium price) and how much will be exchanged (competitive equilibrium quantity) at that price.
Excess DemandOccurs when consumers want more than suppliers provide at a given price. This situation results in a shortage.
Excess SupplyOccurs when suppliers provide more than consumers want at a given price. This situation results in a surplus.
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4.4 Supply and Demand in Equilibrium
Exhibit 4.10 Demand Curve and Supply Curve for OilECO1020 2020 Fall
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4.4 Supply and Demand in Equilibrium
Exhibit 4.11 Excess SupplyECO1020 2020 Fall
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4.4 Supply and Demand in Equilibrium
Exhibit 4.12 Excess DemandECO1020 2020 Fall
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It’s time to revisit the question:
Why do brown eggs cost more than white eggs?
4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
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4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
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4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
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4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
Ready for another one? Why do the price of roses increase right before Valentine’s Day?
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4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
Change in Demand for Roses
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4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
Then why doesn’t the price of beer increase right before Super Bowl Sunday?
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4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
Change in Market for Roses and Beer
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4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
Both the Demand Curve and Supply Curve Shift Right
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4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
The Demand Curve Shifts Right and the Supply Curve Shifts Left
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4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
The Demand Curve Shifts Left and the Supply Curve Shifts Right
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4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
Both the Demand Curve and the Supply Curve Shift Left
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4.4 Supply and Demand in EquilibriumCurve Shifting in Competitive Equilibrium
Effects of Shifts of Demand and Supply
Chan
ge in
Sup
ply
Change in DemandIncr.
Demand Decr.
Demand Incr. Supply Equil. P ?
Equil. Q
Equil. P
Equil. Q ?Decr. Supply Equil. P
Equil. Q ?
Equil. P ?
Equil. Q ECO1020 2020 Fall
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4.5 What Would Happen If the Government Tried to Dictate the Price of Gasoline?
One more question: Why is there a
parking problem on campus?
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4.5 What Would Happen If the Government Tried to Dictate the Price of Gasoline?
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How to estimate demand or supply curve?
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• The observed price and quantity sold cannot be used to estimate demand or supply function (curve)
• Estimation of demand curve requires exogenous changes in supply while demand is held constant