Professional sports leagues are cartels, and economists are keenly interested in how cartels behave. But their work is cut out for them, as the many player statistics available to the fan are not matched by an abundance of team and league financial information that would enable economists to test theories regarding labor economics. So they use a combination of economic theory, simple probability and statistical concepts to answer questions about the effects of free agency on competitive balance, for instance, or the causes of rising ticket prices and the impact of a new stadium on local economy.