THE TEACHING ECONOMIST - William A. McEachern                 

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Issue 30, Spring 2006

William A. McEachern, Editor

Making the Grade

Grades are usually the most contentious part of teaching. In a move towards transparency, course syllabi are becoming more explicit in how numerical scores map into letter grades. But even with that, numerical differences across instructors can rile students, who view such differences as unfair. For example, why should a passing grade in one course be 70 when it's 50 in another?

To see how grade structures differ across instructors, I surveyed a random sample of 44 online syllabi for principles of economics courses that mapped percentage scores into letter grades. Based on a scale of 100, the lowest passing score in the sample was 30 and the highest passing score was 77. That's a 47-point difference! For 28 of the 44 syllabi, the lowest passing score was 60. Here is the distribution of passing scores for the entire sample (with multiple courses at that score in parentheses): 30, 45, 50 (4), 55 (4), 56, 60 (28), 63, 65, 68, 70, and 77.

The lowest score earning an A- was 80 and the highest was 92. For 35 of the 44 courses, A- began at 90. The greatest spread between the lowest passing score and the lowest A- score was 60 points and the smallest spread was 15 points. The spread was 30 points for 32 of 44 syllabi. Despite outliers, most courses reflect a traditional grade structure, where students must score at least 60 to pass and at least 90 for an A-.

How rigid are these mappings? I surveyed each syllabus for any evidence of flexibility after the fact. In five of the 44 courses, the instructor reserved the right to expand grade intervals. Of course, those grading on a curve would be less likely to put their numerical grade structure on the syllabus to begin with. Why put it out there if you may change it?

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