Measuring the Deviations from Perfect Competition: International Evidence

We use aggregated macroeconomic data for 43 countries to test the microeconomic condition for Perfect Competition, whereby the price level is equal to the marginal cost in the long run. We postulate two forms of Perfect Competition in the macro data: a weaker-form and a stronger-form. The former exists if the price level and the marginal cost share a common long-run trend; i.e., cointegrated. The latter exists if the market price and the marginal cost are _equal _in the long run.