In a poll of students in grades 6 through 12, 13 reported that ...

[craiczarry]

In a poll of students in grades 6 through 12, 13 reported that someone had seriously threatened to shoot them in the past year. This percentage was based on a sample of 2,508 students in 96 schools for which the principal had to give consent before the students could be surveyed. Give one possible explanation of why the sample may not have been representative of the population of all students in grades 6 through 12.

Question 2

A survey of people applying for a mortgage showed that among white people with a bad credit rating, 90 were approved for mortgages, whereas among black people with a bad credit rating, 81 were approved. What confounding variable could also explain the apparent racial difference in the percentage of approved mortgages?

[Swizqar]

Answer to Question 1

The principals who taught in high crime neighborhoods may have been more willing to participate in the survey than principals in low crime neighborhoods.

Answer to Question 2

Amount of other assets and income level are both potential confounding variables.

[craiczarry]

Gracias!

[scikid]

Thanks for the timely response, appreciate it