Market Integration, Efficiency of Arbitrage, and Imperfect Competition: Methodology and Application to U.S. Celery

This paper develops and applies a methodology to test for efficiency of interregional commodity arbitrage. Application of the methodology requires only time-series data on prices for alternative cities, regions, countries, or product forms. Yet, the approach is capable of generating evidence on a number of market parameters including market integration, arbitrage efficiency, the magnitude of marketing margins, product substitutability, and competitiveness of markets. Estimation is based on a switching regression model with three regimes: efficient arbitrage, relative shortage, and relative glut. Results from application of the model to U.S. celery marketing indicated significant departures from efficient arbitrage for both California and Florida celery.