Applied Animal Behaviour Science (October 2000) published a study of the taste preferences of caged cockatiels. A sample of birds bred at the University of California, Davis, was randomly divided into three experimental groups. Group 1 was fed purified water in bottles on both sides of the cage. Group 2 was fed water on one side and a liquid sucrose (sweet) mixture on the opposite side of the cage. Group 3 was fed water on one side and a liquid sodium chloride (sour) mixture on the opposite side of the cage. One variable of interest to the researchers was total consumption of liquid by each cockatiel.

a. What is the experimental unit for this study?

b. Is the study a designed experiment? What type of design is employed?

c. What are the factors in the study?

d. Give the levels of each factor.

e. How many treatments are in the study? Identify them.

f. What is the response variable?

g. Write the regression model for the designed experiment.