Question

A few years​ ago, a certain company introduced a line of​ new, slick swimsuits. Some say that they gave the wearers an advantage in races. In order to test whether the suits were​ effective, suppose that there are 80 swimmers;40 of them are​ professional-level swimmers, and 40 are​ amateur-level swimmers. The designers will ask the swimmers to swim 200metres as fast as possible. It is reasonable to assume that the effects of the suits​ (due to dynamic forces of the​ water) might be different for the two levels of swimmers.

Describe a simple randomized design​ (not blocked) to test whether the slick suits decrease race times. Explain how to assign the swimmers to treatment groups. Choose the correct answer below.

A.Have each simmer wear a slick suit for a 200​-metre race. Record each​ swimmer's time. Ask each swimmer if this time decreased from his or her normal 200​-metre

time.

B.Randomly assign each swimmer to wear either a slick or a​ non-slick suit. Place in a bag 40 tickets that say​ "slick" and 40 that say​ "non-slick." Have each swimmer choose a ticket and use that type of suit in a 200​-metre race. Record each​ swimmer's time.

C.Randomly assign a type of suit to each level of swimmers. Place 2 tickets in a​ bag, one that says​ "slick" and one that says​ "non-slick." Pick one​ ticket, and assign that type of suit to the professional swimmers and the other type of suit to the amateur swimmers. Have them swim a 200​-metre race. Record each​swimmer's time.

D.Let each swimmer choose whether they want to wear a slick suit or a​ non-slick suit, and then have them swim a 200​-metre race. Record each​ swimmer's time.

Answer 1