Reference no: EM132422119

Problem: As horses age, arthritis in their joints, tendons, and ligaments may compromise their ability to flex their legs or bear weight, thus reducing their mobility. Such a reduction in activity can lead to other health concerns. A study is to be conducted to determine which of two injection therapies, polysulfated glycosaminoglycans or sodium hyaluronate, is more effective in promoting joint health and reducing the onset of equine arthritis. Researchers will randomly select 180 horses from 10 different large veterinary practices around the country. All the horses will be more than 12 years old, and their owners have given consent to participate in the study. Changes in joint health will be evaluated after six months of treatment.

Required:

Question 1: What would be an advantage of adding a control group to the design of the study?

Question 2: Assuming a control group is added, explain how you would assign the 180 horses to the three treatment groups for a completely randomized design.

Question 3: 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 horse. How would you decide which one of these two variables to use as a blocking variable?