Letter to the Editor,
A student takes a course and averages 89.99% at the end of the semester, after the professor has rounded her/ his total numerical grade to two significant digits after the decimal point. His letter grade is a B in the absence of curving, although it is clear to everyone (professor, student, and potential employer) that this number is almost 90%. The student’s grade remains a B, however, since the professor uses a straight scale, i.e., no curving. Why not make an exception and make this grade an A, you may ask. Because, a cutoff point has to be established somewhere. (Another student may earn an average of 87.83% and argue why not assign me an A, etc.)
Professors spend time converting numerical grades to letter grades (with or without curving), and the administration spends resources (i.e., software) to convert the letter grades back to a numerical scale, to give GPAs (or QPAs, depending on your institution) on a 4.0 or 9.0 scale, depending on your institution. However, doing so results in aggregation bias, since every value between, for example, 70% and 79.99% is treated as a C, whereas it is clear the student who scores 79.99% has done better than the student who has managed a 70%. In oft used student terms, when arguing against an assigned grade, this grading scheme is “not fair!”
Letter grades or grading for that matter did not appear until the 19tcentury when Yale University assigned grades as best, worse, and worst. Some schools attempt to reduce aggregation bias by including +/- boxes next to the letter grades. Some schools use double letters such as AA, AB, etc., again to reduce aggregation bias. Why not make the scale continuous (0% – 100%) and not bother with discrete scales such as the ones we have in place now (A, B, C, D, F or A+-, B+-, C+-, …, or AA, BA, BB, …)?
Note that, the suggested method does not preclude curving. If the overall class grades are low, a professor can still curve, and for example, add 30 (or however many points are needed) to each student’s numerical average, to boost the grades.
I suggest we drop the letter grading system. The benefits would be:
•more accuracy in assigning grades (i.e., no more aggregation bias)
•fewer student appeals for grade changes
•system-wide time saved in converting from numerical to letter grades and then back to a numerical scale again
•avoiding confusion across countries/institutions that use a 4.0 or 9.0 or other scale to convert numbers to letters
The costs would be:
•dealing with resistance to make a change across the academic community
•risking to be among the first to establish this system
I suggest we switch to a continuous numerical scale since everyone (students, professors, and potential employers) interprets percentages the same way (0%-100%) and since benefits appear to outweigh costs.
Dr. Füsun F. Gönül