| Abstract: | Distinct discrete decisions made by the same economic actor are likely to be correlated, particularly those decisions involved in transportation demand. These correlations may be due to economic interactions among the decisions, or to heterogeneity, or both. This paper develops an econometric method that can distinguish among these possibilities and applies this method to analyzing motor carrier deregulation. One overall goal of the Motor Carrier Act of 1980, which substantially reduced federal regulation, was to promote greater competition in the industry. Other things equal, the more competition in an industry, the less concentration. However, concentration has been increasing among general freight carriers since deregulation. The positive correlations found between the decisions to acquire broker authority and to be a general freight carrier could be due to joint economies between broker authority and general freight carriage, in which case the two interact as economic complements, or to heterogeneity among motor carrier licensees. In the first case, but not the second, deregulation of broker authority could lead to increased concentration in the general freight sector. Empirically, we find that the decisions are correlated due to heterogeneity, but do not interact. Thus, increased concentration in the general freight sector must be attributed to other causes. |
