Internet searches and cell phones. Pew Internet and American Life Project asked a random sample of 2485 cell phone users whether they had used their cell phone to look up health or medical information. Of these, 422 said “Yes.”21
(a) Pew dialed cell phone telephone numbers at random in the continental United States in an attempt to contact a random sample of adults. Based on what you know about national sample surveys, what is likely to be the biggest weakness in the survey?
(b) Act as if the sample is an SRS. Give a large-sample 90% confidence interval for the proportion p of all cell phone users who have used their cell phone to look up health or medical information.
(c) Three out of the five most popular health-related searches on cell phones have to do with sex: “pregnancy,” “herpes,” and “STD” (sexually transmitted diseases). Sex-related queries don’t even show up on Google and Yahoo’s lists of the top five health searches on computers. What do you think explains the difference in the topics of health-related searches on cell phones versus computers? When drawing conclusions from a sample, you must always be careful to take into account the relevant population.View less »
