Hi, Bob! Be sure to review your types of sampling designs & think about how unlikely it would be to get exactly 50 student responses from each college class using simple random sampling. Simple random sampling uses a numbered list, and randomly generated numbers are used to choose subjects from that list. While there is a minute possibility that you could get equal numbers from each classification, it is extremely improbable. Most likely an equal number of students were chosen from each classification, so that opinions from all classifications were equally represented. If they had chosen fewer students from each class, there would be the possibility that not enough student opinions were represented. More student opinions per class would be great, but obviously require more time investment to collect & compile data. The students should have intended for each student on campus to have equal chance of selection for the survey & that each undergraduate class was adequately represented, so they likely used the probability sampling technique known as stratified sampling.
