THEORY OF DEMAND

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THEORY OF “DEMAND”

Transcript of THEORY OF DEMAND

Page 1: THEORY OF DEMAND

THEORY OF “DEMAND”

Page 2: THEORY OF DEMAND

INTRODUCTION• How much to produce and what price

to charge?• Factors determining demand for a

product.• Explores the relationship between

price and demand for a product.• Examines likely impact of the potential

factors that influence its demand.

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WHAT IS DEMAND?The quantity of a product consumers are willing and able to buy at different prices in a specified time period.

Types of Demand-Direct and derived demands

-Individual and market demand

-Recurring and replacement

-Complementary and competing

-New and replacement demands

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DETERMINANTS OF DEMAND

• Price of Product• Income of Consumer• Price of Related Good• Tastes and Preferences• Advertising• Consumer’s expectation of future Income and Price• Growth of Economy• Seasonal conditions• Population

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DEMAND SCHEDULE• It shows the price and output relationship.• Tabular representation of price and demand.

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DEMAND CURVE

• The geometrical representation of demand schedule is called the demand curve.

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LAW OF DEMAND

• As the price of a good rises, quantity demanded of that good falls.

• As the price of a good falls, quantity demanded of that good rises.

• Ceteris paribus.

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DEMAND FUNCTION• When we express the relationship between demand

and its determinant mathematically, the relationship is known as demand function.

• The demand for product X can be written in functional form as-

Dx= f (Px, Y, Po, T, A, Ef, N )

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EXCEPTIONS TO THE LAW OF DEMAND

• Inferior Goods• Snob Appeal• Demonstration Effect• Future Expectation of Prices• Insignificant proportion of income spent• Goods with no Substitutes

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CHANGE IN DEMAND VS. CHANGE IN QUANTITY DEMANDED

• A shift of the entire demand curve to a new position is called change in demand.

• Changes in non-price determinants of demand.

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QUANTITY DEMANDED• Fluctuations in price, another determinant of demand,

cause movement along the demand curve.

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Why the demand curve slope downwards?

• Law of diminishing marginal utility.• Income effect.• Substitution effect.• New consumers.• Multiple use of commodity.

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ELASTICITY OF DEMAND• Elasticity of demand is defined as the responsiveness of the

quantity of a good to changes in one of the variables on which demand depends-

Price of the commodity Income of the Consumer Various other factor

DEFINATION-’’The elasticity of demand measures the response of the demand for the commodity to change in price”.

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PRICE ELASTICITY OF DEMAND• The price elasticity of demand is the percentage change in

quantity demanded divided by the percentage change in price.

P rice e las tic ity o f d em an d =P ercen tag e ch an g e in q u an tity d em an d ed

P ercen tag e ch an g e in p rice

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PRICE ELASTICITY OF DEMAND

/

/P

Q Q Q PE

P P P Q

Point Definition

Arc Definition 2 1 2 1

2 1 2 1P

Q Q P PE

P P Q Q

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Perfectly Inelastic Demand: Elasticity Equals 0 city of Demand

Copyright©2003 Southwestern/Thomson Learning

$5

4

Quantity

Demand

1000

1. Anincreasein price . . .

2. . . . leaves the quantity demanded unchanged.

Price

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Inelastic Demand: Elasticity Is Less Than 1

Quantity0

$5

90

Demand1. A 22%increasein price . . .

Price

2. . . . leads to an 11% decrease in quantity demanded.

4

100

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Unit Elastic Demand: Elasticity Equals 1

Copyright©2003 Southwestern/Thomson Learning

2. . . . leads to a 22% decrease in quantity demanded.

Quantity

4

1000

Price

$5

80

1. A 22%increasein price . . .

Demand

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Elastic Demand: Elasticity Is Greater Than 1

Demand

Quantity

4

1000

Price

$5

50

1. A 22%increasein price . . .

2. . . . leads to a 67% decrease in quantity demanded.

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Perfectly Elastic Demand: Elasticity Equals Infinity

Quantity0

Price

$4 Demand

2. At exactly $4,consumers willbuy any quantity.

1. At any priceabove $4, quantitydemanded is zero.

3. At a price below $4,quantity demanded is infinite.

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INCOME ELASTICITY

• The degree of responsiveness of the demand for the commodity to a change in the income of the consumer.

• It is defined as Ratio of percentage change in the quantity demanded of a commodity to the percentage change in the income of consumer

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• Negative ( inferior commodities )

• Zero ( neutral commodities )

• Greater than zero but less than 1( normal commodities )

• Greater than unity ( Luxurious commodity )

INCOME ELASTICITY

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• Point Definition

/

/I

Q Q Q IE

I I I Q

• Arc Definition 2 1 2 1

2 1 2 1I

Q Q I IE

I I Q Q

INCOME ELASTICITY

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Cross Elasticity of Demand (CED)

• Cross price elasticity (CED) measures the responsiveness of demand for good X following a change in the price of good Y (a related good)

• CED = % change in quantity demanded of product A% change in price of product B

• With cross price elasticity we make an important distinction between substitute products and complementary goods and services.

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SubstitutesPrice of Good S

Quantity demanded of Good T

Demand

Two Weak Substitutes

P1

P2

Goods S and T are weak substitutes

A rise in the price of Good S leads to a small rise in the demand for good T

tea and coffee

+

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Complements

Price of Good X

Quantity demanded of Good Y

Demand

Two Close Complements

P2

P1

Goods X and Y are close complements

A fall in the price of good X leads to a large rise in the demand for good Y

Petrol and petrol car

-

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Goods with zero cross-price elasticity of demand .

INDEPENDENTPrice of Good A

Quantity demanded of Good B

Demand

P1

P2

P3

Goods A and B have no relationship.

A fall in the price of good A leads to no change in the demand for good B

Therefore the cross-price elasticity of demand is zero

salt!

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