Question

A survey of Chicago. A New Yonk Times/Kaiser founda tion survey of Chicagoans showed that they are deeph the sample Is lU Kalsdeept 28 dissatisfied with the direction of their city, distrustful 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 ba sis of which member had the most recent birthday. (a) The survey wants the opinion of an individu 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 birhday Wihy is his precferable to simply intervier ing 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. (o) Are there residents of Chicago who have telephone numbers that cannot be reached by the described? Explain why this could be a d (Hint: How are telephone numbers phone users?) cell to rs assigned to cell

Answer 1

a) As per Battaglia in the paper titled ,"A Comparison of Address-Based Sampling (ABS) Versus Random-Digit Dialing (RDD) for General Population Surveys", picking the adult with the most recent birthday is a valid way of random sampling for within households sample. Even asking questions to the adult picking up the phone is correct, but the first method gives more unbiased responses.

b) The population this survey wants to describe is Chicago residents. They want them to answer questions on governance viz. direction of the city, behavior and response of the police force etc. Both the landline and cell phone users are important because older residents might not be using cell phones. They also need to be included. Some households would be cell phone only. So, cell phone users also need to be surveyed to get a truly representative sample.

c) Yes, unlisted and listed telephone numbers were accessed by randomly adding digits to complete the telephone numbers. This could be a problem because a lot of numbers might not be responded to as those numbers might not exist at all. It is a waste of research resources.