4. In each of the following examples, identify the sampling method used.

a. Instructors are interested in knowing what eating techniques their students are utilizing.

Rather than assessing all students, the researchers randomly select one specific class to

comprise their sample.

b. National Geographic collects data on its readers by asking them to fill out and send in a

survey from the March issue.

c. A psychologist is studying the sleep patterns of the 3960 students in her basement. She

decides to start by asking a random sample of 30 students how many hours of sleep they

get weekday nights. The psychologist assigns each student a number from 0001 to 3960

and uses a computer to randomly generate a list of 30 numbers to select the students for

the sample.