A student performs an experiment to test the effects of a special diet on the cholesterol content of chicken eggs. He obtained 20 chickens from two different breeders. Half of the chickens were fed the special diet, and half were fed a diet of standard chicken feed, purchased at a local feed store. The student found that cholesterol levels in the eggs from chickens fed the special diet were lower than the levels found in the eggs of the other group, and he concludes that his special diet should be marketed to farmers. Do you see any problems with this study? How would you improve the design?