Petsmart is a retail store that sells pet supplies. Suppose Petsmart is interested in studying how sensitive its customers are to price discounts. However, Petsmart also is curious if its price discounts are more likely to promote sales among customers who are dog owners. Using an electronic app, Petsmart conducts an experiment that manipulates different levels of price discounts across two groups of customers: (1) those who own dogs and (2) those who own at least one pet BUT no dogs.

(a) Based on the description above, which experimental design would be more appropriate? A randomized block design or a factorial design? Explain your answer.

(b) Suppose a member of the research team argues that the results of the experiment were affected by a history effect. Describe an example of how a history effect could lead to misleading results of the treatment effect.