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Some Factors That Influence Course Evaluations—And Some That Don’t

Some course characteristics that are not under an instructor’s control can influence student ratings of instruction (commonly called course evaluations). While these effects do not always represent bias, they should be taken into account in interpreting course evaluations fairly and accurately.

The research investigating relationships between course characteristics and student ratings of instruction suggests that there are some small but noteworthy correlations.

  • Smaller class sizes tend to get higher ratings than larger ones. It is not clear whether this relationship reflects differences in teaching methods typically used in the two contexts, or whether it is an effect of size alone.
  • Classes in mathematics and the natural sciences tend to receive lower ratings than those in other disciplines.
  • Elective courses tend to get slightly higher ratings than required courses, especially if a required course is outside a student’s major.
  • Graduate student instructors tend to receive lower ratings than appointed faculty.

The effect of any one of these factors may not be great, but a combination could affect a teacher’s mean rating significantly.

Instructors often fear that student ratings are unduly influenced by factors that may be unrelated to effective teaching, such as:

  • course difficulty
  • workload
  • grading leniency
  • instructor popularity
  • gender.

The research has generally found little or no consistent relationship between such factors and student ratings (Centra, 1993).

What about students’ grades?

Some studies have shown a modest correlation between expected grade and course ratings (Braskamp

and Ory, 1994). However, this can be accounted for by the likelihood that students who learn more tend both to get higher grades and give higher ratings. Braskamp and Ory conclude, “In sum, faculty do not receive high student ratings only because they give high grades.”


Braskamp, L. A. & Ory, J. C. (1994). Assessing faculty work: Enhancing individual and institutional performance. San Francisco: Jossey-Bass.

Centra, J. A. (1993). Reflective faculty evaluation: Enhancing teaching and determining faculty effectiveness. San Francisco: Jossey-Bass.

Perry, J. D. (2002). Course Evaluation Practices at IU Bloomington. Office of the Vice Chancellor for Academic Affairs and Dean of the Faculties.

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