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Sig figs - How strict to be as a grader?

  1. Jan 14, 2017 #21
    My practice has been to deduct approximately 5% of the point value for the problem. So if the problem is 5 pts, I usually award 3 for correct set-up, and 1.5 for accurate calculations and half a point for significant digits/units/etc.
  2. Jan 14, 2017 #22


    Staff: Mentor

    Half a point out of 5 total points is 10%, double the 5% you said you usually deduct.
  3. Jan 14, 2017 #23

    Vanadium 50

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    Yeah, but to one significant figure... <ducking and running>
  4. Jan 14, 2017 #24
    It's a half point for sig figs /units, or any other info that might be needed. So, it's a quarter of a point for each taken individually. Sorry if that was unclear.
  5. Jan 14, 2017 #25
  6. Jan 14, 2017 #26
    Just some perspective. In my first year of graduate school and as a TA, my course instructor required us to take account some students were solving the numerical part of the problem with a slide rule, and most were using a pocket calculator. Intermediate steps using slide rule can lose a lot of precision. Even now, (I suppose, because I have not been teaching for a while), you may have to account for different constants.

    For example, my course instructor told us, if your students want to use g = 10 m/s2, that is OK. We are not interested in the numerical answer, but if they know the method. I dislike computer scoring for similar reasons. The computer can sometimes require the student to be "exact", and be unforgiving.

    I prefer to take a relaxed attitude towards significant figures. I think you should bring to the student's attention that the number of places the calculator supplies is (usually) to many places. I would bring up this issue with the course instructor and your fellow grad TA's considering you want uniformity in course grading amont all the TA instructors, anyway.
  7. Jan 14, 2017 #27

    Andy Resnick

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    I have the same attitude- I only get cranky if the student simply copies out the 12 digits their calculator spits out.
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