John comes up with the following methods for generating unbiased samples from shoppers at a mall.

I. Ask random strangers in the mall

II. Always go to the mall at the same time of day

III. Go to different places in the mall

IV. Don't ask questions the same way to different people

Which of these techniques represents the best way of generating an unbiased sample?

Which of the following is a reasonable selection requirement for a survey designed to predict presidential election results?

These two samples are about students' favorite subjects. What inference can you make concerning the students' favorite subjects?