Anecdotal data is personal data, this data varies from one person to another person.
The friend choice of best instructor does not apply for entire college students. Other students have a different view for statistics instructors, it may be the same or other students have another subject instructor as the best instructor. It is an individual data, it is not the same for all the students, so this data does not apply to entire college's students.
This is anecdotal evidence, which could not provide the complete evidence for the best instructor in the college.
No, because it is anecdotal evidence which is not the same for all persons.