Question

A shoe company wants to test an updated model of a running shoe on its wear after one month of running. They recruit 50 people who run on a regular basis to participate in their study. They will have the runners wear the shoes when they run for two months. After two months, the wear on the shoes will be determined using the depth of the tread and flexibility of the toe box. The wear between the new model and the original model will then be compared.

Which of the following describes a matched pairs design?

A. The subjects are numbered 1–50, and these numbers are put into a random number generator. The first 25 random numbers, ignoring repeats, represent the subjects assigned to the new model group. The remaining 25 subjects will wear the original model.
B. The subjects’ names are written on equal-sized slips of paper and placed into a hat. A researcher then reaches in and pulls out 25 slips of paper. These subjects are assigned to the new model group. The remaining 25 subjects will be assigned to the original model group.

C. The 50 subjects will receive both models of shoes. The runner will flip a coin and if it lands on heads, they will wear the new model on their right foot and the original model on their left foot. Then after one month, they will change and use the new model on their left foot and the original model on their right foot. After the second month, the wear for each model will be determined and compared for the 50 runners.

D. The 50 subjects are grouped based on running ability. Twenty runners classify themselves as competitive runners and the remaining 30 classify themselves as recreational runners. For the competitive group, the runners’ names are written on equal-sized slips of paper and placed into a hat. The slips are shuffled, and the first 10 runners wear the new model of shoes and the other 10 wear the original model. The same procedure is used to assign the shoes to the recreational group.

Answer 1

Explanation:

C. The 50 subjects will receive both models of shoes. The runner will flip a coin and if it lands on heads, they will wear the new model on their right foot and the original model on their left foot. Then after one month, they will change and use the new model on their left foot and the original model on their right foot. After the second month, the wear for each model will be determined and compared for the 50 runners.

In a matched pairs design, each subject is tested with both treatments, and the order in which they receive the treatments is randomly determined. This helps control for any individual differences between subjects, as each subject serves as their own control. Option C describes this type of design. Options A, B, and D do not involve each subject being tested with both treatments.