Now suppose that instead of the 75 students having been randomly selected from the entire student body, the 75 students had been randomly selected only from the engineering classes at the college (for the sake of convenience).
Address the following two issues regarding the effect of such a change in the study design:
- Would we still be mathematically justified in using the t-test for obtaining conclusions, as we did previously?
- Would the resulting conclusions still address the question of interest (which, remember, was to investigate the drinking habits of the students at the college as whole)?