A New York Times/Kaiser foundation survey of Chicagoans showed that they are deeply dissatisfied with the direction of their city, distrustful of their police force, and divided along racial lines. The poll is based on telephone interviews conducted April 21–May 3, 2016, with 1123 adults who live in Chicago. The samples of telephone exchanges for both landlines and cell phones were randomly selected by a computer from a complete list of exchanges in Chicago (the telephone exchange is the three digits following the area code). Within each exchange, random digits were added to form a complete telephone number, thus permitting access to listed and unlisted numbers alike. Landline respondents are chosen at random within each household on the basis of which member had the most recent birthday.

a. The survey wants the opinion of an individual adult, but a landline phone reaches a household in which several adults may live. In that case, the survey interviewed the adult with the most recent birthday. Why is this preferable to simply interviewing the person who answers the phone?
b. What is the population that this survey wants to describe? Why do you think it is important to include both landline and cellular phones in your sample?
c. Are there residents of Chicago who have telephone numbers that cannot be reached by the survey method described? Explain why this could be a problem. (Hint: How are telephone numbers assigned to cell phone users?)