Chapter 4.2, Problem 81E

(a)

To determine

To explain the statement carefully.

Explanation of Solution

In this question, a nutrition experimenter intends to compare the weight gain of newly weaned male rats fed Diet A with that of rats fed with Diet B. The statement was that if the ten rats from Litter $\text{1}$ were fed Diet A the effects of genetics and diet would be confounded and the experiment would be biased in favor of Diet A. Thus, this statement means that if all rats from litter $\text{1}$ were fed Diet A and if these rats gained more weight, we would not know if this was because of the diet or because of genetics and initial health.

(b)

To determine

To describe a better design for this experiment.

Answer to Problem 81E

The better design would be a randomized block design.

Explanation of Solution

In this question, a nutrition experimenter intends to compare the weight gain of newly weaned male rats fed Diet A with that of rats fed with Diet B. Thus, for the better design for this experiment we should use a randomized block design with the litters as blocks. For each of the litters randomly assign half of the rats to receive Diet A and the other half to receive Diet B. This will allow researchers to account for the differences in weight gain caused by the differences in genetics and initial health.