What Does It Mean To Me?
Elasticity of Demand
Elasticity of Supply
Supply, Demand, and
Taxation

“The elasticity (or responsiveness) of demand in a market is great or small according as the amount demanded increases much or little for a given fall in price, and diminishes much or little for a given rise in price.”
--Alfred Marshall, Principles of Economics

The law of demand tells us that consumers will respond to a decline in a product’s price by buying more of that product.
That amount can vary considerably by product and over different price ranges for the same product.

The responsiveness, or sensitivity, of quantity demanded to a change in the price of a product is measured by the concept of

Demand for some products is such that consumers are highly responsive to price changes;
, for example: restaurant meals, steak, cars.
The demand for such products is said to be relatively elastic, or simply
.

For other products, consumers are quite unresponsive to price changes;
, for example: salt, milk, soap.
For such products, demand is relatively inelastic or simply
.

Economist measure the degree of price elasticity or inelasticity of demand with the coefficient E d defined as:
E d
= percentage change in quantity demanded of product X percentage change in price of product X
(E d
= Elasticity of demand)

These percentage changes are calculated by dividing the change in price by the original price and the consequent change in quantity demanded by the original quantity demanded. Thus, our definition can be restated as follows: change in quantity demanded of X change in price of X
E d
=
original quantity demanded of X original price of X

Another way to state the equation would be using the Greek letter delta, , meaning change in…….
E d
=
Q d
/Q d ave
P/P ave

Economists give two reasons:
1) Choice of Units
2) Comparing products

1)
If we use absolute changes, our impression of buyer responsiveness will be arbitrarily affected by the choice of units. Using percentages avoids this problem. A particular price decline is 33 percent whether measured in terms of dollars ($1/$3) or pennies (100 cents/300 cents).

2)
By using percentages, we can correctly compare consumer responsiveness to changes in the prices of different products. It makes little sense to compare the effects on quantity demanded of (1) a
$1 increase in the price of a $10,000 auto with (2) a $1 increase in the price of a $1 can of cola. Here, the price of an auto is rising by .01 percent while the price of cola is up by 100 percent.

We know from the downsloping demand curve that price and quantity are inversely related.
Thus, the price elasticity coefficient of demand
E d will always be a negative number.
As an example, if price declines, then quantity demanded will increase. This means that the numerator in our formula will be positive and the denominator negative, yielding a negative E d
. For an increase in price, the numerator will be negative but the denominator positive, again yielding a negative E d
.
Economists usually ignore the minus sign and present the absolute value of the elasticity coefficient to avoid ambiguity.

d
We can interpret the coefficient of price elasticity of demand as follows:
1) elastic demand
2) inelastic demand
3) unit elasticity

Demand is said to be elastic if a specific percentage change in price results in a larger percentage change in quantity demanded .
Then E d
> 1.
Example: If a 2 percent decline in a price results in a 4 percent increase in quantity demanded, then demand is elastic and
.04
E d
= .02 = 2

A small percentage change in price leads to a larger percentage change in quantity demanded.
P
I
R
C
E
P
1
P
0
P
0
Q
1
Q d
Q
0
QUANTITY
D
2
Relatively elastic demand
E d
> 1

When we say demand is “elastic,” we do not mean that consumers are completely responsive to a price change. In that extreme situation, where a small price reduction would cause buyers to increase their purchases from zero to all they could obtain, economists say demand is perfectly elastic .
You will see in later chapters that such a demand applies to a firm, for instance, a blueberry grower, selling its product in a purely competitive market.

P
I
R
C
E
P
1
P
0
0
Q
1
P
A small percentage change in price will change quantity demanded by an infinite amount.
Q d
D
2
Perfectly elastic demand
E d
=
Q
0
QUANTITY

If a specific percentage change in price is accompanied by a smaller percentage change in quantity demanded, demand is said to be inelastic. Then E d
< 1.
Example: If a 3 percent decline in price leads to only a 1 percent increase in quantity demanded, demand is inelastic and
.01
E d
= .03 = .33

P
I
R
C
E
P
1
P
0
0
A change in price leads to a smaller percentage change in quantity demanded.
P
Relatively inelastic demand
E d
< 1
Q d
Q
1
Q
0
QUANTITY
D
1

When we say demand is “inelastic,” we do not mean that consumers are completely unresponsive to a price change. In that extreme situtation, where a price change results in no change whatsoever in the quantity demanded, economist say that demand is perfectly inelastic .
Examples include an acute diabetic’s demand for insulin or and addict’s demand for heroin.

P
I
R
C
E
P
1
P
0
P
D
1
The quantity demanded does not change regardless of the percentage change in price.
Perfectly inelastic demand
E d
= 0
0
Q
0
= Q
1
QUANTITY

The case separating elastic and inelastic demands occurs where a change in price and the accompanying percentage change in quantity demanded are equal.
Example: A 1 percent drop in price causes a 1 percent increase in quantity demanded. This special case is termed unit elasticity because
E d
= 1, or unity. In this example:
.01
E d
= .01 = 1

The percentage change in quantity demanded is the same as the percentage change in price that caused it.
P
I
R
C
E
P
1
P
0
P
0
Q d
Q
1
Q
0
QUANTITY
D
1
Unit elastic demand
E d
= 1

P
I
R
C
E
P
1
P
0
0
2
Q
When a demand curve is relatively steep, such as D
0 in this graph, its price elasticity is relatively inelastic.
When a demand curve is relatively flat, such as D
1
, its price elasticity is relatively elastic.
D
1
Relatively elastic
D
0 Relatively inelastic
Q
1
Q
0
QUANTITY

• Available substitutes
• Proportion of income
• Luxuries vs necessities
• Time

Available Substitutes
The larger the number of close substitutes, the greater the elasticity .
If the price increases, consumers may select a relatively lower-priced substitute instead.
Examples may include:
• Butter => Margarine
• Pepsi => Coca Cola
• Texaco gasoline => Hess gasoline

Proportion of Income Spent on the Good
The smaller the proportion of income spent on a good, the lower its elasticity of demand . If the amount spent on a good relative to income is small, then the change in price on one’s income will also be small.
Example:
• 100% increase in price of salt vs. 100% increase in price of an automobile.
• 50% increase in price of private education vs. 50% increase in cost of textbooks.

Luxuries vs Necessities
The demand for “necessities” tends to be priceinelastic; that for “luxuries” price-elastic. A price increase will not significantly the amount of a necessity consumed. If the price of a luxury rises, an individual need not buy them and will suffer no great hardship without them.
Examples
(necessities):
• Bread
• Electricity
• Appendectomy
Examples
(Luxuries):
• Caribbean cruise
• Emerald ring
• Lexus

The Amount of Time Since the Price
Change
The more time that people have to adapt to a new price change, the greater its elasticity of demand . Immediately after a price change, consumers may be unable to locate good alternatives or easily change their consumption patterns.

Total revenue (TR) is the total amount the seller receives from the sale of a product; it is calculated by multiplying the product price (P) by the quantity demanded and sold (Q). In equation form:
TR = P x Q
Total revenue and the price elasticity are related.
Indeed, perhaps the easiest way to infer whether demand is elastic or inelastic is to employ the total-revenue test, where we observe what happens to total revenue when product price changes.

Elastic Demand
If demand is elastic, a decrease in price will increase total revenue. Even though a lesser price is received per unit, enough additional units are sold to more than make up for the lower price.
TR = P x Q
TR = P x Q

Elastic Demand and Total Revenue
P
$10
$5 a b
A c
At point A, total revenue is $400 ($10 x 40), or area a + b.
At point B, the total revenue is $500 ($5 x
100), or area b + c.
Total revenue has increased by $100.
B
We can also see in the graph that total revenue has increased because the area b + c is greater than
D elastic area a + b, or c > a.
0 20 40 60 80 100 Q

Inelastic Demand
If demand is inelastic, a price decrease will reduce total revenue. The modest increase in sales will not offset the decline in revenue per unit, and the net result is that total revenue declines.
TR = P x Q
TR = P x Q

Inelastic Demand and Total Revenue
P
$10
$5 b a
A c
0 10 20 30 40
At point A, total revenue is $300 ($10 x 30), or area a + b.
At point B, the total revenue is $200 ($5 x
40), or area b + c.
Total revenue has decreased by $100.
D
B inelastic
Q
We can also see in the graph that total revenue has decreased because the area a + b is greater than area b + c, or a > c.

1) Bumper Crops
Increases in the output of most farm products arising from a good growing season or increase in productivity will cause to decrease both the farm products and the total revenues
(or incomes) of farmers.

2) Automation
The impact of technological advances on employment depends in part on the elasticity of demand for the product or service that is involved.
If a firm installs technology that replaces 1000 workers, who are then laid off, the savings from the cost reduction could be passed on to consumers. The effect of the price reduction on sales will depend on the elasticity of the product.
An elastic demand could increase sales to a point where some of the workers might be rehired. An inelastic demand will result in only minimal increase in sales.

3) Airline Deregulation
In the 1970s, deregulating the airlines caused increased profits for the carriers in the short term, because it increased price competition among the airlines, thus lowering airfares. Lower fares, and an elastic demand for air travel, increased revenues. Filling the airplanes to capacity increased revenues more than the costs and increased profits.
Profits did not last, however, because of rising fuel prices, persistent fare wars, and the entry of competitors on profitable routes.

4) Excise Taxes
The government selects certain goods and services with which to levy excise taxes by paying attention to elasticity of demand. If a $1 tax is levied on a product and 10,000 units are sold, tax revenue will be $10,000. If government then raises the tax to $1.50 and the consequent higher price reduces sales to 5000, tax revenue will decline to $7500. A higher tax on a product with an elastic demand will reduce revenue, therefore, governments seek products with inelastic demands, such as liquor, gasoline and cigarettes.

5) Drugs and Street Crime
Is an addict’s demand for crack cocaine and heroin highly elastic? This belief is typically used by law enforcement to reduce supply by intercepting drug shipments. If this is true, then the street price to addicts will rise sharply while amounts purchased will decrease slightly. This will result in greater revenues for drug dealers. Because the income of the addict comes from actually causes crime.
Proponents of drug legalization contend that drugs should be treated like alcohol because the war on drugs has been unsuccessful and the associated costs are too great.

If the demand for drugs is inelastic then drug “busts” reduce the supply of drugs, which raises the price, and reduces quantity supplied.
Price of
Drugs
Price of
Drugs
S
2
P
2 S
1
P
1
Q
2
Q
1
D
Quantity of Drugs
Quantity of Drugs

Another option is drug education, which reduces demand, which lowers the price, and reduces quantity supplied.
Price of
Drugs
Price of
Drugs
S
2
P
1
P
2 S
1
P
2
P
1
S
Q
2
Q
1
D
Quantity of Drugs
Q
2
D
2
Q
1
D
1
Quantity of Drugs

6) Minimum Wage
Critics say that a minimum wage, if it is above the equilibrium market wage, moves employers upward along their downsloping labor demand curves toward lower quantities of labor demanded, thus causing unemployment-
-especially among teenage workers. Conversely, workers who remain employed received higher incomes with a minimum wage than otherwise.
Research suggests that the demand for teenage labor is inelastic, with Ed possibly as low as 0.15 or 0.25. If correct, this means income gains associated with the minimum wage exceed income losses. The argument would be stronger if the demand for teenage workers were elastic.

When the government mandates a the minimum price of something, it is called a PRICE FLOOR and it keeps the market from reaching equilibrium.
S The demand for labor diminishes while the supply of labor increases causing a surplus.
$5
$4
$3
$2
$1
E
0 1 2 3 4 5 6 7 8 9 10
D
Labor

Supply is said to be elastic if the quantity supplied responds substantially to changes in price.
A small percentage change in price leads to a larger percentage change in quantity supplied.
S
2
P
I
R
C
E
P
0
P
1
P
Relatively elastic supply
Q d
E d
> 1
0
Q
1
Q
0
QUANTITY

Supply is said to be inelastic if the quantity supplied responds slightly to changes in price.
S
2
A small percentage change in price leads to a smaller percentage change in quantity supplied.
P
I
R
C
E
P
0
P
1
P
Relatively inelastic supply
Q d
E d
< 1
0
Q
1
Q
0
QUANTITY

Elasticity of Supply is dependant upon the sellers’ flexibility in changing the amount they produce.
For example: Beachfront property in
Florida has an inelastic supply because we cannot produce more of it.
Manufactured goods such as microwave ovens, televisions, and cars are elastic because the producers can easily adjust production of a good more or less.

When a tax on tea is levied on consumers, the sellers will share part of the tax burden.
P
0 is the equilibrium price WITHOUT the tax.
P
1 is the price sellers will receive.
P
2 is the price consumers will pay.
PRICE
($2.50) P
2
($2.20) P
0
($2.00) P
1
($.50)
0
Q
1
Q
0
E
S w/o tax
($.50)
D
1
D
0
QUANTITY

A payroll tax puts a wedge between the price that workers receive and the amount producers pay.
P labor
$5
$4
$3
$2
$1
E
0 1 2 3 4 5 6 7 8 9 10
S labor
D labor
Q labor

When supply is more elastic than demand, the burden of the tax falls primarily on consumers.
P consumers pay
P
$5
P w/o tax
$4
E
$3
P producers receive
$2
$1
0 1 2 3 4 5 6 7 8 9 10
D
Q
S

In the late 1980s, Governor
Martinez of Florida placed a tax on luxury items in the State of Florida.
Why was this tax repealed a few years later??

When demand is more elastic than supply, the burden of the tax falls primarily on producers.
P consumers pay
$5
P w/o tax
$4
$3
P producers receive
$2
$1
P
E
0 1 2 3 4 5 6 7 8 9 10
S
Q
D

Project by:
Virginia H. Meachum
Coral Springs High School
Sources:
Principles, Problems, and Policies, by Campbell McConnell &
Stanley Brue
Exploring Economics, by Robert Sexton
Principles of Economics, by N. Gregory Mankiw
Notes by Florida Council on Economic Education and FAU
Center for Economic Education
Notes by Foundation for Teaching Economics