 Boyum’s model was criticized by another expert in the case, Dr. Finkelstein, who complained that the model did not take into consideration systematic differences between trips. Presumably, smugglers will tend to carry larger quantities as they become more experienced. When they carry larger quantities, it should be more likely they would be apprehended. If the trip effect holds, the data would mostly be about advanced smugglers who tend to carry more than beginners. No empirical evidence for or against the trip effect theory could be found. Information on the number of previous trips was missing from the data so an appropriate regression model for the trip effect could not be developed. On other other hand, Judge Weinstein argued that beginner smugglers do practice swallowing with grapes, and thus the learning curve should not be excessively steep. In addition, beginners are more likely to be apprehended than advanced smugglers. If so, the data would not be biased by the trip effect. Interestingly, information on Nigerian drug smuggling practices undermines the trip effect theory: the drug cartel did not waste money on sending half-filled drug mules, but rather made them practice swallowing balloons weeks prior to their first trip (Treaser 1992; Wren 1999).