Question: The New War over Wal-Mart Today, Wal-Mart employs more people-1.7 million- than any other private employer in the world. With size comes power: Wal-Mart's prices are lower and United Food and Commercial Workers International Union argues that Wal-Mart's wages are also lower than its competitors. Last year, the workers at a Canadian outlet joined the union and Wal-Mart immediately closed the outlet. But does Wal-Mart behave any worse than its competitors? When it comes to payroll, Wal-Mart's median hourly wage tracks the national median wage for general retail jobs.

If the market for retail labour is competitive, explain the potential effect of a union on the wage rates. Draw a graph to illustrate your answer.