Oferta y demanda

Chapter 3
Demand and Supply

Introduction
Newly-minted Ph.D. economists have faced a difficult job market for academic positions in recent years. This is because two factors have simultaneously increased the supply of economics instructors and decreased the demand for their services.

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Learning Objectives
Explain the law of demand Discuss the difference between money prices andrelative prices Distinguish between a change in demand and a change in quantity demanded
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Learning Objectives
Explain the law of supply Distinguish between changes in supply and changes in quantity supplied Understand how supply and demand interact to determine equilibrium price and quantity
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Chapter Outline
The Law of Demand The Demand Schedule Shifts in DemandChapter Outline
The Law of Supply The Supply Schedule Shifts in Supply Putting Demand and Supply Together

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Did You Know That...
Even though overall prices trend steadily upwards, some prices hold steady or decline? The average price of a desktop personal computer has fallen by almost 50 percent? Demand and supply can explain most of relative price changes?

MarketsMarkets
– Arrangements that individuals have for exchanging with one another – Represent the interaction of buyers and sellers

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Markets
Markets
– Markets for gasoline – Markets for labor – Stock market – Market for Super Bowl tickets – Compact disk market

Markets
Markets
– Markets set the prices we pay and receive

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The Law of DemandDemand
– Quantities of specific goods or services that individuals, taken singly or as a group, will purchase at various possible prices, other things being constant

The Law of Demand
Law of Demand
– Quantity demanded is inversely related to price, all things equal

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The Law of Demand
What are we holding constant?
– Income – Price of other goods – Many otherfactors

The Law of Demand
Relative prices versus money prices
– Relative Price
• The price of a commodity in terms of another commodity

– Money Price
• Price we observe today in today’s dollars (absolute, nominal price)

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Money Price versus Relative Price
Money Price
Price Last Year Price This Year

Example: Price per Constant-Quality Unit
Price ThisYear

Relative Price
Price Last Year

Many products, for which you pay one price, contain many features. The right to return an item for a refund may be one feature that is included in the price. Some retailers now are finding ways to unbundle these various features, by offering consumers the option of paying extra if they wish to use them.
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DVDs

$20

$28

$20 = 2.0 $10 $10= 0.5 $20

$28 = 1.75 $16 $16 $28

Videocassettes $10

$16

= 0.57

Table 3-1

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The Demand Schedule
The demand schedule is a table relating prices to quantity demanded. We must consider:
– The time dimension – Constant-quality units

The Individual Demand Schedule

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Figure 3-1, Panel (a)

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The Individual Demand Curve

The HorizontalSummation of Two Demand Schedules

Figure 3-1, Panel (b)

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Figure 3-2, Panel (a)

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The Horizontal Summation of Two Demand Schedules

The Market Demand Schedule for Rewritable CD’s

Figure 3-2, Panels (b), (c), (d)

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Figure 3-3, Panel (a)

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The Market Demand Curve for Rewritable CD’s

Policy Example: Preventing Traffic JamsExpressways in Japan are subject to tolls. Increased toll rates in recent years have resulted in lower traffic volume.

Figure 3-3, Panel (b)

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Shifts in Demand
Scenario
– The federal government gives every student registered in college a rewritable CD drive to use with a personal computer.

A Shift in the Demand Curve
Price per Rewritable CD ($) 5 4 3 2 1 0 D1 D2...