blocks d. experimental unit

a. There are two possible experimental designs. Design A would use a random sample

of 100 consumers. From this group, 20 would be randomly assigned to each of the five recipes, so that each consumer tastes only one recipe. Design B would use a random sample of 100 consumers, with each consumer tasting all five recipes, the recipes being presented in a random order for each consumer. Which design would you recommend? Justify your answer.

b. When asked how the experiment is going, the researcher replies that one recipe smelled

so bad that she eliminated it from the analysis. Is this a problem for the analysis if design B was used? Why or why not? Is it a problem if design A was used? Why or why not? Supplementary Exercises H.R. 2.19 A large health care corporation is interested in the number of employees who devote a substantial amount of time providing care for elderly relatives. The corporation wants to develop a policy with respect to the number of sick days an employee could use to provide care to elderly relatives. The corporation has thousands of employees, so it decides to have a sample of employees fill out a questionnaire. a. How would you define employee? Should only full-time workers be considered? b. How would you select the sample of employees? c. What information should be collected from the workers? Bus. 2.20 The school of nursing at a university is developing a long-term plan to determine the num- ber of faculty members that may be needed in future years. Thus, it needs to determine the future demand for nurses in the areas in which many of the graduates find employment. The school decides to survey medical facilities and private doctors to assist in determining the future nursing demand.

a. How would you obtain a list of private doctors and medical facilities so that a sample

of doctors could be selected to fill out a questionnaire? b. What are some of the questions that should be included on the questionnaire? c. How would you determine the number of nurses who are licensed but not currently employed?

d. What are some possible sources for determining the population growth and health

risk factors for the areas in which many of the nurses find employment?

e. How could you sample the population of health care facilities and types of private

doctors so as to not exclude any medical specialties from the survey? 2.21 Consider the yields given in Table 2.7. In this situation, there is no interaction. Show that the one-at-a-time approach would result in the experimenter finding the best combination of nitrogen and phosphorus—that is, the combination producing maximum yield. Your solution should include the five combinations you would use in the experiment. 2.22 The population values that would result from running a 2 ⫻ 3 factorial treatment structure are given in the following table. Note that two values are missing. If there is no interaction between the two factors, determine the missing values. Factor 2 Factor 1 I II III A 25 45 B 30 50 Vet. 2.23 An experiment is designed to evaluate the effect of different levels of exercise on the health of dogs. The two levels are L 1 — daily 2-mile walk and L 2 — 1-mile walk every other day. At the end of a 3-month study period, each dog will undergo measurements of respiratory and cardiovascular fitness from which a fitness index will be computed. There are 16 dogs available for the study. They are all in good health and are of the same general size, which is within the normal range for their breed. The following table provides information about the sex and age of the 16 dogs.