The importance of product cut and form when estimating fish demand: the case of U.S. Catfish

The absolute price version of the Rotterdam model was used in the estimation of U.S. catfish demand where catfish was differentiated by product cut (whole, fillet, and other) and product form (fresh and frozen). Likelihood ratio tests were used to determine the importance of product form in demand (product form aggregation). Likelihood ratio tests were also used to determine if fresh products were separable from frozen products (product form separability). Product form aggregation was rejected at a probability of 0.999, suggesting that fresh and frozen catfish products are not homogenous. The hypothesis, no product form separability, failed to be rejected at the 0.05 significance level, but was rejected at the 0.01 significance level. Test results suggest that it is more acceptable to focus on a single product group (e.g., frozen products) than to assume that catfish products are perfectly aggregatable across product forms. [JEL classifications: Q11, Q13, Q22]. © 2009 Wiley Periodicals, Inc.