Suppose you are a member of your university's student organization. You

want to survey students on whether they would like to hold a concert at the end of the

year. You decide to survey 50 of the university's 50,000 students. Consider each of the

following scenarios:

a. You remember that there is a large back-to-school gathering happening in the

main square on campus that afternoon, and thousands of students will be

there. You decide to go to this gathering and survey the first 50 people you

come across. Explain why this type of sample may be biased, and how this may

affect your results.

b. Of the university's 50,000 students, about 45,000 are undergraduate students

and 5,000 are graduate students. You decide to use a random number

generator to randomly pick 45 of the undergraduate students, and 5 of the

graduate students (from a student list). Explain why this type of random sample

is not an SRS.

c. You decide that you will use an SRS to pick the 50 students. You take an SRS of

size 50 from the student list. However, upon closer inspection of this sample,

you notice that none of them are graduate students. Wanting to be fair to

graduate students, you decide to take a new SRS of size 50. This time, there are

a few students of each type, and you are satisfied. Explain why this is not a true

SRS.