A footwear company wants to test the effectiveness of its new insoles (soft insole and air-fill insole) designed to prevent shin splints resulting from running. They hire a group of physical trainers and a statistician, who recruits 100 healthy adult runners with the same age range to participate in a study. The statistician randomly assigns the 60 runners to follow the same weekly running schedule, wherein 30 runners will use new insoles and the remaining 30 will use the existing insoles the company already sells. After 10 weeks, the statistician records the number of runners from each group that has developed shin splints. They made sure that the results are valid that they have performed the testing three times for each treatment