Market Structures
Monopoly
Number of Producers
One
Similarity of Products
Unique
Ease of Entry
Hard
Control Over Prices
Some
Oligopoly
Number of Producers
Few
Similarity of Products
Similar
Ease of Entry
Hard
Control Over Prices
Some
Market Failures
Positive Externality
Benefit that falls on someone other than the producer or consumer
Negative Externality
Cost that falls on someone other than the producer or consumer
Perfect Competition
Number of Producers
Many
Similarity of Products
Virtually Identical
Ease of Entry
Easy
Control Over Prices
None
Monopolistic Competition
Number of Producers
Many
Similarity of Products
Differentiated
Ease of Entry
Easy
Control Over Prices
Some