For the following research questions idenify the observation

For the following research questions idenify the observational units and variable (s)

Do all college students who pull an all-nighters tend to have lower grades than those who do not pull all-nighters ?

Solution

In the question the observational units are the college students (because observational units means from which the information to be collect)

And the variable (s) is (are) the grade of the student selected.