The article "Sleepless in School" describes a study of 282 college students. The students were recruited from a
general education psychology course (a course taken by students from different majors) and they were offered extra
credit to fill out an online survey. The survey included questions about the students' sleep health (e.g., hours of sleep during a usual school week) as well as questions about possible social determinants of deficient sleep (e.g., food insecurity, psychological distress).

Answer the following four questions for this observational study.

a) What is the population of interest?

all adults
all students majoring in education psychology
all college students

(b) Was the sample selected in a reasonable way?

Yes, the sample was randomly selected.
No, only college students were represented.
No, the class had students from a variety of majors but it may not be representative of all majors.
No, the sample size is less than 500 which is too small for a large university.

(c) Is the sample likely to be representative of the population of interest?

Yes, the college student population was well represented.
Yes, enough students participated to provide a reasonable estimate of the population.
No, because only students in this class were selected.
No, the population of interest is all adults and only college students were studied.

(d) Are there any obvious sources of bias?

Measurement bias is present because the survey questions were worded poorly.
Nonresponse bias is present because not all students enrolled in the course completed the online survey.
Selection bias is present because students who need extra credit may be overrepresented.
No sampling bias is present