500
A group of researchers want to ask adolescents important questions about their health behaviors, and they want to have a sample that is representative of the entire U.S. population of adolescents. Since they do not have a list of every adolescent who lives in the U.S., which of the following is the best way to obtain a sampling frame?
They should take a sample of schools from a list of all high schools in the U.S., then use the list of students attending those schools