Results indicate that, when comparing the unconditional derived-demand elasticities to the unconditional consumer demand elasticities, significant differences emerge due to the differences in the first-stage estimation procedure between the differential production approach and the Rotterdam model. In comparing the consumer demand price/corss-price elasticities to the derived-demand price/cross-price elasticities, it is clear that use of the Rotterdam model when a production approach should be used can lead to overestimation, underestimation, and incorrect signs in deriving unconditional price effects.