With regard to an undergraduate statistics course, I am developing a standardized list of point deductions with the TAs (doctoral students) so that graders are consistent in what they are taking off intermediate points for. For example, most problems are 10 points total, and my proposed point deductions for intermediate math errors are (for example):
- -2 pts, erroneous +, - , *, /
- -2 pts, erroneous sign, e.g. 3.02 instead of -3.02
- -3 pts, failed to square, e.g. (x) instead of (x)^2
- -3 pts, failed to take square root, e.g. (x) instead of sqrt(x)
If, after grading, you discover on a particular exam that the final answers for five 10-point questions are incorrect because of only making a minor -2 point intermediate error, the student could conceivably obtain a score of 80% on an exam if they missed only -2 points per question (40/50).
However, in statistics, there is a contextual element to every question, not just solving for a numerical answer -- that is, in addition to the worked problem, students need to write a text-based response for the following:
- (2 pts) state whether the hypothesis test is significant or not
- (2 pts) state whether the null hypothesis is rejected or accepted
- (2 pts) state whether the p-value is less than 0.05 or not.
So if there was only one minor (-2 point) intermediate error made, causing an incorrect final numerical answer, the student will also incorrectly respond to the final text-based answers (above) as well.
Thus, would you also take off e.g. -2 points for an incorrect final numerical answer, as well as -6 points for missing the final text-based sub-items listed above?
In other words, would you only deduct -2 points for a complex (multi-step) algebra or calculus question if only a minor intermediate step was erroneous, or would you also deduct for having an incorrect final numerical answer as well?
Maybe I could propose to the TAs to augment the point deduction list with:
- -1 pt, incorrect final numerical answer
- -1 pt, state whether the hypothesis test is significant or not
- -1 pt, state whether the null hypothesis is rejected or accepted
- -1 pt, state whether the p-value is less than 0.05 or not.