as hamsters age, they can develop a disease with a side effect of severe diarrhea. hamsters with this side effect experience severe dehydration from the diarrhea, which can be fatal. a study is to be conducted to determine which of two antibiotics, baytril or albon, is more effective as a remedy for combating this side effect. researchers will randomly select 300 hamsters from 10 different large veterinary practices around the country. all the hamsters will be more than 1 year old, and their owners have given consent to participate in the study. changes in symptoms will be evaluated after six months of treatment.

part a: what would be an advantage of adding a control group to the design of the study? (2 points)

part b: assuming a control group is added, explain how you would assign the 300 hamsters to the three treatment groups for a completely randomized design. (4 points)

part c: rather than using a completely randomized design, one group of researchers proposes blocking on veterinary clinics whereas another group of researchers wants to block on breed of hamster. how would you decide which one of these two variables to use as a blocking variable?