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Principles of Economics by Fred M Gottheil. prepared by Adnan A, Alshiha. Chap. 3 SUPPLY AND DEMAND. © 1999 South-Western College Publishing. What is Supply and Demand?. A model of price behavior in competitive markets. Note that Demand is not. The same as wants The same as needs
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Principles of Economicsby Fred M Gottheil prepared by Adnan A, Alshiha Chap. 3 SUPPLY AND DEMAND ©1999 South-Western College Publishing
What is Supply and Demand? A model of price behavior in competitive markets
Note that Demand is not • The same as wants • The same as needs • necessarily the same as the actual quantity purchased
The Law of Demand When price increases the quantity demanded decreases and vice versa, ceteris paribus ©1999 South-Western College Publishing
What assumption is always made when the price changes? Ceteris paribus or everything else stays the same-abbreviated cet.par. ©1999 South-Western College Publishing
What is a Demand Schedule? Shows the specific quantity of a good or service that people are willing and able to buy at different prices ©1999 South-Western College Publishing
Price Quantity Demanded $10 0 $9 1 $8 2 $7 3 $6 4 $5 5 7 ©1999 South-Western College Publishing
What is a Demand Curve? A graph that depicts the relationship between price and quantity demanded ©1999 South-Western College Publishing
P1 Demand Curve P2 Q2 Q1 9 ©1999 South-Western College Publishing
Reasons for the Law of Demand?? • The substitution (relative price) effect • The real income effect
What is a change in Demand? A change in the amount demanded of a good that is caused by factors other than a change in the price of that good ©1999 South-Western College Publishing
Shift in Demand Curve P D2 D1 Q ©1999 South-Western College Publishing 12
A rightward shift in the demand curve is an increase in demand, a leftward shift is a decrease in demand.
What causes a shift in Demand? • Change in tastes • Income changes • Changes in Population • Changes in the prices of related goods • Changes in Expectations
Income changes: 2 possibilities: • Normal goods: as income rises, demand rises, cet. par. • Inferior goods: As income rises, demand falls, cet. par.
Changes in related goods prices: 2 cases: • Substitute goods: As the price of Y increases, the demand for X increases • Complementary goods: As the price of Y increases, the demand for X decreases
Changes in future price expectations The expectation of a future rise in price leads to an increase in demand now, cet. par.
What is Market Demand? The sum of all individual demands in a market
NOTE - KNOW THE DIFFERENCE BETWEEN A CHANGE IN THE QUANTITY DEMANDED AND A CHANGE IN DEMAND ©1999 South-Western College Publishing
Changes in demand vs. changes in quantity demanded • Changes in quantity demanded only caused by changes in the products own price, a movement along a demand curve • Changes in demand--a shift in the demand curve caused by factors other than the price of the product
P P P1 P2 D1 D D Q1 Q2 Q Q A change in demand A change in quantity demanded
Do you understand? Do you really understand?????
Which of the following would increase the current demand for cd’s? a. A decrease in the price of cd’s • A decline in the teenage population • A lower cost for producing cd’s • An expectation of a drop in cd prices • A decrease in the price of cd players The correct answer is…….E
1. According to the "Law of Demand," as the price of a good increases a. the demand for the good increases. b. the demand for the good decreases. c. the quantity demanded increases. d. the quantity demanded decreases. 2. Tea and Coffee are ____________. Peanut butter and jelly are ____________. a. complements; substitutes b. complements; complements c. substitutes; complements d. substitutes; substitutes
3. Which of the following will increase the demand for pencils? a. a decrease in the price b. a decrease in the student population c. a decrease in the price of pens d. a decrease in the price of erasers
The supply side of the market Supply refers to willingness and ability to produce something
The Law of Supply As price rises, the quantity supplied rises, cet. par.
Reasons for the Law of Supply? • Monetary incentives • The Law of Increasing Opportunity Costs
What is a Supply Schedule? Shows the specific quantity of a good or service that suppliers are willing and able to provide at different prices ©1999 South-Western College Publishing
Price Quantity Supplied $5 0 $6 1 $7 2 $8 3 $9 4 $10 5 30 ©1999 South-Western College Publishing
What is a Supply Curve? Depicts the relationship between price and quantity supplied ©1999 South-Western College Publishing
P2 S Supply Curve P1 Q2 Q1 32 ©1999 South-Western College Publishing
What is Market -day Supply? A market situation in which the quantity of a good supplied is fixed, regardless of price ©1999 South-Western College Publishing
S P2 P1 Supply Curve Q 34 ©1999 South-Western College Publishing
What is a change in Supply? A change in the amount supplied of a good that is caused by factors other than a change in the price of that good ©1999 South-Western College Publishing
Shift in Supply P S1 S2 Q 36 ©1999 South-Western College Publishing
A rightward shift in the supply curve is an increase in supply, a leftward shift is a decrease in supply.
What causes a shift in Supply • Technology changes • Changes in resource prices • Changes in the number of suppliers • Changes in other good prices • Changes in expectations
Increases in supply can be caused by: Improved technology Lower resource prices Greater number of firms Expected lower future prices
NOTE - KNOW THE DIFFERENCE BETWEEN A CHANGE IN THE QUANTITY SUPPLIED AND A CHANGE IN SUPPLY ©1999 South-Western College Publishing
Changes in supply vs. changes in quantity supplied • Changes in quantity supplied only caused by changes in the products own price, a movement along a supply curve • Changes in supply--a shift in the supply curve caused by factors other than the price of the product
S P S1 S P P2 P1 Q1 Q2 Q Q A change in supply A change in quantity supplied
Supply and demand together • Put supply and demand curves on the same graph • Intersection gives the equilibrium price and quantity
Price S PE D QE Quantity PE and QE represent the equilibrium price and quantity
What is Equilibrium Price? The price that equates the quantity demanded and the quantity supplied ©1999 South-Western College Publishing
What happens if price is below equilibrium? A shortage, or excess demand, arises
At P2, QD > QS, thus a shortage or excess demand exists S P2 D Shortage QS QD 47
How is the shortage eliminated? The price rises, leading to a decrease in quantity demanded and an increase in quantity supplied.
What happens if price is above equilibrium? A surplus, or excess supply, arises
At P1, QD < QS, thus a surplus or excess supply exists Surplus S P1 D QS QD 50