Muddling about the Middle

Suppose you get a 73 on a physics test. Is this an excellent score? Why or why not?

What if half of the class scored 65 or below? Does this change how you think about your grade? What difference, if any, did the extra information make? When we evaluate a statistic, we must have a frame of reference with which we can compare that statistic. We need some idea of a "middle" score.


Consider this sample group of test scores again:

100, 100, 99, 98, 92, 91, 91, 90, 88, 87, 87, 85, 85, 85, 80, 79, 76, 72, 67, 66, 45

Which would you say is the "middle" score: 87 or 83.95? Is there another score you might choose?

  • If you chose 87 as the "middle" score, you picked a statistic known as the median.

  • If you chose 83.95 as the "middle" score, you picked a statistic known as the mean.

    If you haven't chosen yet, please hurry up and decide, before this horrid background color burns away your optic nerves.


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