La risposta, secondo un paper pubblicato nel Journal of Political Economy, è che queste valutazioni possono essere distorte dato che:
Professors can inflate grades or reduce academic content to elevate student evaluations.
Il paper teorizza dunque un modello migliore per valutare la bravura di un professore. L’idea è semplice: se un Professore insegna Calculus 1, la performance dei suoi studenti nel corso di Calculus 2, sarà una proxy della bravura del professore stesso. Di conseguenza questo lavoro
uses a unique panel data set from the United States Air Force Academy (USAFA) in which students
are randomly assigned to professors over a wide variety of standardized core courses. The random assignment of students to professors, along with a vast amount of data on both professors and students, allows us to examine how professor quality affects student achievement free from the usual problems of self-selection. Furthermore, performance in USAFA core courses is a consistent measure of student achievement because faculty members teaching the same course use an identical syllabus and give the same exams during a common testing period. Finally, USAFA students are required to take and are randomly assigned to numerous follow-on courses in mathematics, humanities, basic sciences, and engineering. Performance in these mandatory follow-on courses is arguably a more persistent measurement of student learning. Thus, a distinct advantage of our data is that even if a student has a particularly poor introductory course professor, he or she still is required to take the follow-on related curriculum.
Questi i loro risultati:
Results show that there are statistically significant and sizable differences in student achievement across introductory course professors in both contemporaneous and follow-on course achievement. However,our results indicate that professors who excel at promoting contemporaneous student achievement, on average, harm the subsequent performance of their students in more advanced classes. Academic rank, teaching experience, and terminal degree status of professors are negatively correlated with contemporaneous value-added but positively correlated with follow-on course value-added. Hence, students of less experienced instructors who do not possess a doctorate perform significantly better in the contemporaneous course but perform worse in the follow-on related curriculum.