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shminux comments on Exams and Overfitting - Less Wrong Discussion

12 Post author: robot-dreams 06 January 2015 07:35PM

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Comment author: shminux 06 January 2015 11:13:37PM 3 points [-]

Asking to make the connection is OK if this skill (connecting several topics together to solve a problem) has been practiced before explicitly in that same course. Final exam is not the place to demand it for the first time in the course.

Comment author: JoshuaZ 07 January 2015 12:06:35AM 2 points [-]

There are different degrees of this. For example, (I know I keep going back to Calc I), on the final I had told the students that there would be implicit differentiation. But the implicit differentiation in question required combining it with logarithmic differentiation to handle a long product (which I said as a hint in the problem). In that case, they didn't have to "make" the connection but they did need to handle both techniques together.

Comment author: shminux 07 January 2015 03:13:17AM 0 points [-]

If they saw combinations of, say, implicit differentiation, product rule and chain rule before, and they know when to use logarithmic differentiation, then it is certainly OK to combine them, especially if you give a hint to that effect.

Comment author: JoshuaZ 07 January 2015 03:15:03AM 1 point [-]

So where is the line? Can you maybe give examples of what would seem to be unacceptable degrees of making connections for an exam in an intro level course?

Comment author: gwillen 07 January 2015 10:00:10AM *  3 points [-]

I once had a physics professor (with a reputation for being tough) give an exam problem which required some slightly unusual calculus trick which -- though surely covered in a prerequisite math course -- had never been used anywhere else in the physics course. [I unfortunately don't remember the details; this would have been ~2004.] It was something I think most people in the class would not have had a problem with in isolation. But in the context of the exam, under time pressure, it just wasn't something that came to mind to try. The professor subsequently expressed confusion about why everybody in the class bombed that question, since it only involved doing things which -- in isolation -- we should all have been able to do.

I don't think I'd call the question "unacceptable", but I think the professor's mystification reflected an unfortunate misjudgment about how hard it is to think creatively under time pressure.