Refer to the Passage Below to Answer the Questions That

Refer to the passage below to answer the questions that follow.
Dell Computers dramatically increased its consumer advertising,resulting in Dell becoming the top-selling personal computer brand.Consumers could purchase a Dell computer only directly from Dell,either by calling the toll-free number or visiting Dell's website.One of Dell's popular television commercials included Steve,a young man who would usually say,"Dude,you're gettin' a Dell." Audiences really liked Steve and the ads he appeared in,and in fact,that's when Dell's sales started to skyrocket.However,Dell has stopped that campaign and has moved on to others.
-Dell's media buyers purchased television commercial slots based on audience estimate measures and then compared those estimates to the actual audience.What else should the Dell media buyers consider when using these exposure numbers to evaluate impact?