College students' evaluations of teaching and grade inflation

This study investigated the question: Has the use of student evaluations of teaching effectiveness been a contributing factor to a trend of grade inflation in a mid-sized, public university in the upper midwest? Aggregating the data for 983,491 student evaluations of more than 37,000 course sections, this study examined the trends in the percentage of students expecting the grades of A or A- and students' composite ratings of teaching effectiveness in courses offered between 1980 and 1999. Statistically significant second order polynomial trends over 40 semesters were found for the percentage of A/A- grades and for students ratings of teaching effectiveness. The percentage of students expecting A/A- grades increased steadily by a total of more than 10 percentage points during the 1990s after remaining stable during the 1980s. Student ratings of teaching gradually, but steadily, increased by more than one-tenth of a point after remaining relatively stable during the first half of the 1980s. The predictive relationship between student ratings of teaching and expected grades was significant even after variables related to alternative explanations were statistically controlled. The conclusion that, although generally valid as measures of teaching effectiveness, college students' ratings of instruction may be used in ways that raise questions of consequential validity, specifically by encouraging grade inflation, was supported.