This module introduces the concept of a perfectly competitive market. It is a benchmark construction, but it accurately models many markets in our economy. We will understand equilibrium outcomes in both the short run and the long run. We will understand how to analyze shocks to these equilibria.

Analysts can predict equilibrium outcomes with some degree of certainty. We want to construct a measure of efficiency that will allow us to evaluate the attractiveness of these equilibrium market outcomes. After using this metric to consider the efficiency of the competitive market, we will introduce a different market structure, monopoly, and use our efficiency metric to evaluate the equilibrium resource allocation under monopoly.

Perfectly competitive markets have many sellers. Monopoly has one seller. But much economic activity takes place in markets with just a handful of very large producers. These are called oligopoly markets. We will look at collusive arrangements among a small number of rivals, and then will use simple game theoretic techniques to model equilibrium.

Sometimes even markets that appear to be capable of great efficiency in resource allocation, such as the perfectly competitive market, can fall short of efficiency. Economists call this market failure. In this module, we will consider information issues and the impact on efficiency. We will also introduce externalities (spillovers) such as pollution and model these impacts.