The topic for this questionnaire is "student life, academics, athletics", which is an important part of the question when determining if non-responses are important. In this case ChatGPT gets it correct, but explains the reason very poorly.
"the 90 students who did respond to the questionnaire are representative of the entire population"
How can anyone know this without knowing the size of the freshman class? For that matter, how does anyone know that 120 would have been a good number?
Secondly, non-responses may actually correlate to the topic questions! For all anyone knows, students may not respond because
- too busy studying
- too busy partying
- too busy with intramural sports
- too disillusioned, feeling that it will not make a difference.
Etc