Question

A scientist wants to test how therapies A and B improve the eyesight of rats. She has 20 rats to use, but their vision is different, which might affect how much vision they improve. The scientist decides to group the four rats with the worst vision in one group, the next four rats with second-to-worst vision in another group, etc., until the final group has the best vision. Then, from each group she randomly selects two rats to receive therapy A, and the remaining two rats in each of the groups get therapy B.

select one or more:

a. The experimental units are therapies A and B.

b. The treatment is the eyesight improved.

c. This is an example of a matched pairs experiment.

d. The experimental units are the 20 rats.

e. This is an example of a block design.

f. This is an example of a completely randomized experiment.

g. The treatments are therapies A and B.

Answer 1

a. The experimental units are therapies A and B. - False, the experimental units are rats

b. The treatment is the eyesight improved. - False, the treatment are therapies A and B

c. This is an example of a matched pairs experiment. False, different random samples were used for different therapies (treatment). This is a completely randomized experiment.

d. The experimental units are the 20 rats. - True

e. This is an example of a block design. - True, the blocking factor is vision

f. This is an example of a completely randomized experiment. Truedifferent random samples were used for different therapies

g. The treatments are therapies A and B.- True

The correct statements are -

d. The experimental units are the 20 rats.

e. This is an example of a block design.

f. This is an example of a completely randomized experiment.

g. The treatments are therapies A and B.