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Chapter 4: Q 65. (page 255)

Stronger players A football coach hears that a new exercise program will increase upper-body strength better than lifting weights. He is eager to test this new program in the off-season with the players on his high school team. The coach decides to let his players choose which of the two treatments they will undergo

for three weeks—exercise or weight lifting. He will use the number of push-ups a player can do at the end of the experiment as the response variable.

(a) Which principle of experimental design does the coach’s plan violate? Explain how this violation could lead to confounding.

(b) Comment on the coach’s choice of response variable.

Short Answer

Expert verified

(a) It could lead to confounding as players were not assigned arbitrary to treatments.

(b) It is that just the number of pushups cannot test power of upper body.

Step by step solution

01

Given Information

The coach decides to let his players choose which of the two treatments they will undergo for three weeks—exercise or weight lifting. He will use the number of push-ups a player can do at the end of the experiment as the response variable.

02

To explain how this violation could lead to confounding.

Treatments will not be randomly assigned. It depends on player which treatment he wants. They will be relaxed.

Poorer player should prefer exercise and stronger player should do weightlifting.

Random allocation is principle of laboratory design that is ignored.

03

To describe coach’s choice of response variable.

Number of pushups cannot predict the result. It may shape part and contribute to successful performance in addition to other steps also.

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