Call it Moore's law of US higher education: the quantity and quality of work that undergraduates must do to get top grades halves every decade. This is an exaggeration, of course, but many readers will recognize the sentiment. Is it just the jaded perception of cynical academics? On the contrary: the evidence suggests that there is a real problem of grade inflation in degree courses, especially at private universities. And the assessment of teachers by students, as well as parents' demands that they get what they think they've paid for, are making the problem worse.

Course evaluations were intended to give the instructor feedback about how well he or she was doing. But they rapidly became a favoured tool of deans, tenure and promotion committees because they were quantifiable. Now there is an implicit understanding that if instructors give good grades, they will not be judged too severely by students. New faculty often grade more harshly than other members of the department, only to be ‘punished’ by students. Deans who believe that this doesn't happen are deluding themselves.

Also worrying is the idea — particularly evident at costly private universities — that students and their parents believe they are paying for a degree that will lead to a good job, rather than for a good education that will help them to think independently. The pressure on teachers to appease demanding students and parents by awarding high grades is obvious.

The consequences are all too clear. Anecdotal evidence suggests that there is a general unwarranted upward creep in grades (http://ctl.stanford.edu/Tomprof/index.shtml). More objectively, the fact that graduate schools rely for admission criteria almost exclusively on the results of standardized tests, rather than on universities' individual grading, points to a systematic failure to ensure that grading standards are being maintained.

What to do? More universities should focus seriously on improving the instructional abilities of their faculty in programmes — mandatory for new instructors — to videotape classes and analyse them with the faculty member to highlight strengths and weaknesses. And evaluations should take note of thoughtful individual comments by students, rather than relying on scores, or be abandoned.