Chapter fifteen
Download
1 / 38

Chapter Fifteen - PowerPoint PPT Presentation


  • 51 Views
  • Uploaded on

Chapter Fifteen. Market Demand. From Individual to Market Demand Functions. Think of an economy containing n consumers, denoted by i = 1, … ,n. Consumer i’s ordinary demand function for commodity j is. From Individual to Market Demand Functions.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Chapter Fifteen' - tatum-harper


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Chapter fifteen

Chapter Fifteen

Market Demand


From individual to market demand functions
From Individual to Market Demand Functions

  • Think of an economy containing n consumers, denoted by i = 1, … ,n.

  • Consumer i’s ordinary demand function for commodity j is


From individual to market demand functions1
From Individual to Market Demand Functions

  • When all consumers are price-takers, the market demand function for commodity j is

  • If all consumers are identical then where M = nm.


From individual to market demand functions2
From Individual to Market Demand Functions

  • The market demand curve is the “horizontal sum” of the demand curves of the individual consumers.

  • For example, suppose there are only two consumers; i = A,B.


From individual to market demand functions3
From Individual to Market Demand Functions

p1

p1

p1’

p1’

p1”

p1”

20

15


From individual to market demand functions4
From Individual to Market Demand Functions

p1

p1

p1’

p1’

p1”

p1”

20

15

p1

The “horizontal sum”of the demand curvesof individuals A and B.

p1’

p1”

35


Elasticities
Elasticities

  • Elasticity is a measure of the “sensitivity” of one variable with respect to another.

  • The elasticity of a variable X with respect to a variable Y is defined as


Economic applications of elasticity
Economic Applications of Elasticity

  • Economists use elasticities to measure the sensitivity of

    • quantity demanded of commodity i with respect to the price of commodity i (own-price elasticity of demand)

    • demand for commodity i with respect to the price of commodity j (cross-price elasticity of demand).


Economic applications of elasticity1
Economic Applications of Elasticity

  • demand for commodity i with respect to income (income elasticity of demand)

  • quantity supplied of commodity i with respect to the price of commodity i (own-price elasticity of supply


Own price elasticity of demand
Own-Price Elasticity of Demand

  • Q: Why not just use the slope of a demand curve to measure the sensitivity of quantity demanded to a change in a commodity’s own price?

  • A: Because then the value of sensitivity depends upon the chosen units of measurement.


Own price elasticity of demand1
Own-Price Elasticity of Demand

is a ratio of percentages and so has nounits of measurement. Hence own-priceelasticity of demand is a measure of the sensitivity of quantity demanded to changes in own-price which is independent of the choice of units of measurement.


Arc and point elasticities
Arc and Point Elasticities

  • If we measure the “average” own-price elasticity of demand for commodity i over an interval of values for pi then we compute an arc-elasticity, usually by using a mid-point formula.

  • Elasticity computed for a single value of pi is called a point elasticity.


Point own price elasticity
Point Own-Price Elasticity

An example of computing a point own-priceelasticity of demand.Suppose pi = a - bXi. Then Xi = (a-pi)/b and

Therefore,


Point own price elasticity1
Point Own-Price Elasticity

pi = a - bXi*

pi

a

a/b

Xi*


Point own price elasticity2
Point Own-Price Elasticity

pi = a - bXi*

pi

a

a/b

Xi*


Point own price elasticity3
Point Own-Price Elasticity

pi = a - bXi*

pi

a

a/2

a/2b

a/b

Xi*


Point own price elasticity4
Point Own-Price Elasticity

pi = a - bXi*

pi

a

a/2

a/2b

a/b

Xi*


Point own price elasticity5
Point Own-Price Elasticity

pi = a - bXi*

pi

a

own-price elastic

(own-price unit elastic)

a/2

own-price inelastic

a/2b

a/b

Xi*


Point own price elasticity6
Point Own-Price Elasticity

A second example of computing a pointown-price elasticity of demand.

Suppose

Then

so


Point own price elasticity7
Point Own-Price Elasticity

pi

everywhere alongthe demand curve.

Xi*


Revenue and own price elasticity of demand
Revenue and Own-Price Elasticity of Demand

  • If raising a commodity’s price causes almost no decrease in quantity demanded then sellers’ revenues will rise.

  • Hence own-price inelastic demand will cause sellers’ revenues to rise as price rises.


Revenue and own price elasticity of demand1
Revenue and Own-Price Elasticity of Demand

  • If raising a commodity’s price causes a very large decrease in quantity demanded then sellers’ revenues will fall.

  • Hence own-price elastic demand will cause sellers’ revenues to fall as price rises.





Revenue and own price elasticity of demand5
Revenue and Own-Price Elasticity of Demand

so if

then

and a change to price does not altersellers’ revenue.


Revenue and own price elasticity of demand6
Revenue and Own-Price Elasticity of Demand

but if

then

and a price increase raises sellers’revenue.


Revenue and own price elasticity of demand7
Revenue and Own-Price Elasticity of Demand

And if

then

and a price increase reduces sellers’revenue.


Revenue and own price elasticity of demand8
Revenue and Own-Price Elasticity of Demand

In summary:

Own-price inelastic demand;price rise causes rise in sellers’ revenue.

Own-price unit elastic demand;price rise causes no change in sellers’revenue.

Own-price elastic demand;price rise causes fall in sellers’ revenue.


Marginal revenue and own price elasticity of demand
Marginal Revenue and Own-Price Elasticity of Demand

  • A seller’s marginal revenue is the rate at which revenue changes with the number of units sold by the seller.


Marginal revenue and own price elasticity of demand1
Marginal Revenue and Own-Price Elasticity of Demand

Let p(q) denote the seller’s inverse demand function; that is, the price at which the seller can sell q units. Then

so



Marginal revenue and own price elasticity of demand3
Marginal Revenue and Own-Price Elasticity of Demand

says that the rate

at which a seller’s revenue changeswith the number of units it sellsdepends on the sensitivity of quantitydemanded to price; i.e., upon theof the own-price elasticity of demand.



Marginal revenue and own price elasticity of demand5
Marginal Revenue and Own-Price Elasticity of Demand

Selling onemore unit does not change the seller’srevenue.

If

then

Selling onemore unit reduces the seller’s revenue.

If

then

If

then

Selling onemore unit raises the seller’s revenue.


Marginal revenue and own price elasticity of demand6
Marginal Revenue and Own-Price Elasticity of Demand

An example with linear inverse demand.

Then

and



Marginal revenue and own price elasticity of demand8
Marginal Revenue and Own-Price Elasticity of Demand

p

a

$

a/2b

a/b

q

R(q)

q

a/2b

a/b


ad