A researcher wants to test how diets A and B affect the weight loss of rabbits. She has 20 rabbits to use, but all of the rabbits are different sizes, which might affect how much weight they lose. The researcher decides to group the four smallest rabbits in one group, the next four smallest rabbits in another group, etc., until the final group has the four largest rabbits. Then, from each group she randomly selects two rabbits to have diet A, and the remaining rabbits in the groups have diet B.

Select all that apply:
A. This is an example of a block design.
B. This is an example of a completely randomized experiment
C. This is an example of a matched pairs experiment.
D. The treatments are diets A and B.
E. The treatment is how much weight a rabbit loses.
F. The experimental units are the 20 rabbits.
G. The experimental units are diets A and B

The randomized block designs are used in experiment when there is only one variable of prime importance but along with it there are several nuisance factors. As in this case, the prime variable is the impact on weight of rabbits when they consume one the given diets. However, several nuisance factors are unequal weights of the rabbit, different class of rabbits, eating habits of rabbit, time of feeding etc.

Treatment in an experiment is the independent variable that is varied to measure its impact on the subjects of the experiment.

Here these independent variables are diet type A and B and the subject is the group of 20 rabbits. Subjects are also referred as experimental unit i.e on which the experiment is being conducted

Hence, option A, D and F are correct