This document contains examples of how supply and demand interact in various markets. It discusses how weather destroying part of the lettuce crop shifts the supply curve left, raising prices. For pink salmon, new technology and fishers enter the market, shifting supply right, while income and substitute price changes shift demand left. Refinery issues and oil prices decrease gasoline supply as income growth and SUV popularity increase demand. Land in San Francisco has a vertical supply curve as quantity supplied is fixed, so demand increases only raise prices. Preset ticket prices can cause shortages or surpluses like at Olympics figure skating and curling events.
2. 3A-2
Lettuce
• Supply shifts left for lettuce: Weather destroys part of
the crop.
• Demand doesn’t change: Consumers still want as
much lettuce as before.
• Equilibrium price rises which will reduce the quantity
demanded.
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3. 3A-3
The Market for Lettuce
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Quantity (pounds)
D1
S1
Q1
P1Price(perpound)
S2
Q2
P2
0
4. 3A-4
Pink Salmon
• Supply shifts right for pink salmon:
• New technology
• New fishers enter the industry
• Demand shifts left for pink salmon:
• Increases in consumers’ income
• Reductions in the price of substitutes
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5. 3A-5
The Market for Pink Salmon
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D1
S1
Q1
P1
Quantity (pounds)
Price(perpound)
S2
D2
P2
Q2
0
6. 3A-6
Gasoline
• Supply of gasoline decreases:
• Refinery breakdowns
• Mideast politics and warfare
• Rising price of oil
• Demand for gasoline increases:
• Consumers’ incomes increased
• Low mileage SUVs popular
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7. 3A-7
The Market for Gasoline
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D2
S2
Q1
P2
Quantity (gallons)
Price(pergallon)
S1
D1
P1
Q2
0
8. 3A-8
Land in San Francisco
• Vertical supply curve.
• Quantity supplied fixed and unresponsive to price
changes.
• Demand increase causes price to rise but quantity
stays the same.
• Demand decrease causes price to fall but quantity
stays the same.
• Explains high real estate prices in cities.
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9. 3A-9
The Market for Land in San Francisco
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D1
S
Q0
P1
Quantity (acres)
Price(peracre)
D2
0
P2
b
a
10. 3A-10
Preset Prices
• Preset prices can cause market imbalances.
• Olympics figure skating finals: Preset price results in a
shortage of tickets.
• Olympics curling preliminaries: Preset prices result in
a surplus of tickets.
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This appendix provides additional examples of demand and supply analysis using real-world economic events. This is helpful for those trying to understand or explain current events.
As a result of bad weather, the supply of lettuce decreases and shifts to the left, but demand has not changed because there haven’t been any changes in any of the determinants of demand. When supply decreases, equilibrium price increases and quantity falls.
This market represents the demand and supply of lettuce. Freezing weather decreases the supply of lettuce reflecting lower quantities supplied at every price. The demand for lettuce remains the same after the freeze. The price of lettuce rises and the quantity available in the market is reduced.
Supply shifts due to new technology which increases the catch and lowers the cost of fishing. High profits encourage new fishers to enter the industry. Demand shifts due to increases in consumers’ income causing them to shift away from canned fish such as pink salmon. Reductions in the price of substitutes for pink salmon, such as fresh salmon from the Atlantic, cause the demand for pink salmon to fall.
As a result of the changes in the pink salmon market, supply shifts to the right and demand shifts to the left. In this example, the supply shift was greater than the shift in demand therefore the result is a lower price and higher quantity.
The supply curve for gasoline shifts left due to a decrease in the number of producers, and increases in input costs (oil). The demand curve shifts to the right due to increases in consumers’ income which causes an increase in the demand for the normal good (gasoline) and increased use of automobiles that do not get very good gasoline mileage.
An increase in the demand for gasoline, as shown by the shift from D1 to D2, coupled with a decrease in supply, as shown by the shift from S1 to S2, boosts equilibrium price (here from P1 to P2). In this case, equilibrium quantity increases from Q1 to Q2 because the increase in demand outweighs the decrease in supply.
When a supply curve is upsloping, any change in demand is tempered by a change in quantity supplied. However, when the supply curve is vertical and fixed, any change in demand results only in changes in price; the quantity supplied stays the same no matter what the price is. There is only so much land available in major cities, like San Francisco, therefore when demand increases, the only market response is an increase in price.
Because the quantity of land in San Francisco is fixed, the supply curve is vertical and parallel to the vertical axis. Therefore, when demand changes the only market response is a change in price. In this graph, the demand for land in San Francisco increases from D1 to D2 and causing price to rise from P1 to P2. The supply is the same no matter what the price is.
Due to the shortage of tickets in the formal market, a secondary market develops and tickets sell for higher prices. It is safe to assume that the shortage was caused by the original price being set too low.
Contrast this to the surplus of tickets to the curling preliminaries. Demand is low for this event and tickets were priced too high causing the stands to be relatively empty. Event officials should lower the price to sell more tickets.
In the market for tickets to the Olympic women’s figure skating finals the demand curve, D, and supply curve, S, produce an equilibrium price that is above the P1 price printed on the ticket. At price P1 the quantity of tickets demanded, Q2, greatly exceeds the quantity of tickets available (Q1). The resulting shortage of ab (= Q2-Q1) gives rise to a legal, or illegal, secondary market.
In the market for tickets to the Olympic curling preliminaries the demand curve, D, and supply curve, S, produce an equilibrium price below the P1 price printed on the ticket. At price P1 the quantity of tickets demanded is less than the quantity of tickets available. The resulting surplus of ba (= Q1-Q2) means the event is not sold out.