Researchers conducted a study of the effects of three drugs on the fat content of the shoulder muscles in Labrador retrievers. They divided 80 dogs at random into four treatment groups. The dogs in group A were the untreated controls, while groups B, C, and D received one of three new heartworm medications in their diets. Five dogs randomly selected from each of the four groups received treatment for periods varying from 4 months to 2 years. The percentage of fat content of the shoulder muscles was determined and is given here.

Source df SS MS F ratio p-value Treatments 3 1.0796 3599 3.03 0345 Error 76 9.0372 1189 Totals 79 10.1168