GPA and significant digits

[siserune]

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Because of the averaging over several dozen courses, the “GPA variance” will be about an order of magnitude smaller than the “individual course-grade variance”, and in that sense, the GPA is accurate to an extra digit or so beyond the accuracy of the individual course grades.

Is this true? I would imagine if grades were assigned as, for example, 3.3 +/- 0.1, the average value (i.e. the GPA) would have to be reported as a confidence interval, and not given a 3 digit definite value.

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<p>Yes, it is true. Confidence intervals could be used or not, but they don’t change the point: if the width of the confidence interval is 0.2 for the individual grades, then the interval around the GPA would still be an order of magnitude smaller, and it would also still be meaningful to report the center of the GPA interval to 1-2 more digits of accuracy than the course grades themselves.</p>