|
Perfect Competition
|
Monopolistic competition
|
Oligopoly
|
Monopoly
|
Number of firms
|
Many
|
Many
|
A few
|
One
|
Freedom
of entry
|
Easy
|
Easy
|
Difficult
|
Very
difficult
|
Nature
of product
|
Identical/
Homogeneous
|
Differentiated
|
Homogeneous /
Differentiated
|
Unique
|
Implications
for
demand
curve
|
Horizontal
|
Downward sloping – elastic
|
Downward sloping – inelastic
|
Downward sloping – most
inelastic
|
Average
size of
Firms
|
Small
|
Relatively
small/ Medium
|
Large
|
Very large
|
Possible
consumer
demand
|
Low
|
Low/Medium
|
Medium
/ Strong
|
Strong
|
Profit
making
possibility
|
None
|
Low
/ Medium
|
Medium
/Strong
|
Strong
|
Government
intervention
|
None
|
None
|
Medium
|
Strong
|
A
new example
|
Wheat
|
Optical
stores
|
Steel
|
Postal
Services
|
Control over pricing
|
None
|
Low
|
Moderate/
Substantial
|
Substantial
|
FOUR different market structures with graphs below comparing
the demand, costs, revenue, output and profits:
Perfect
Competition
At an output of QE, the average cost is C, and the average
profit is equal to the distance PC. The
total profit is equal to the average profit times the quantity produced. This is represented graphically by yellow
shaded area. Image Source Page:http://jimluke.com/teachingportfolio/examples/unit8/jimsguide.html
Monopolistic
Competition
D is an elastic
demand curve with its associated marginal revenue curve MR. ATC and MC are the normal U-shaped cost
curves. The area Pbq0 represents total
revenue. Similarly, Caq0 represents
total costs. If we subtract costs from
revenue, we get an economic profit, which is represented by shaped area PbaC.
Monopoly
We show the firm producing output 20 quantity, the level of output
where MR = MC.
At that level of output the firm sells its product for $10 per unit. This means the firm's total revenue is 10 x
20 = 200. At 20 units of output ATC
= 7, so total cost is 20 x 7 =
140. So profit = TR - TC = 200 - 140 = 60.
Or average profit is 10 - 7 = 3 per unit, so profit
is 20 x 3 = 60.
Image Source Page: http://www.econweb.com/Sample/Monopoly/ProfitMax13.html
Oligopoly
The discontinuity in the marginal revenue (MR) curve is the
result of the kink in the demand curve.
The MC is the original marginal cost curve. Quantity Q is the
profit-maximizing output that results in price P.
Image Source Page: http://www.businessbookmall.com/economics_26_oligopoly.html