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Topic: ABS Random Rectangles
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Posts: 144
Registered: 12/6/04
ABS Random Rectangles
Posted: Dec 28, 1996 8:18 AM
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ABS "Random Rectangles" activity (_Student Guide_, p.99):

I've done this one several times, always with the same results:
rectangles chosen randomly do a better job of estimating the mean
population area than the "guess method" and the "judgment method".

But I have found I need to organize things quite carefully, in advance.
For example, if anyone had told me four years ago that you have to
_explain_ carefully to students how to use a random-number table, I would
have scoffed. But I was wrong. It needs to be explained and rehearsed
in advance. (Using the TI-83 to generate the random numbers probably
would be easier; I'll try that next time.)

I use an overhead copy of the page of rectangles, and supply a sheet with
prompts on which their results are recorded. I also arrange it so I can
check their use of a random number table. Even then, I get strange
results at times, like the student who guessed that the average area on
the page was 20, despite the fact that the largest area on the page is

This is a second opportunity to say to students that "You can't expect
yourself to behave randomly!" Of course, it also supplies an opportunity
to talk about selection bias.

Bruce King
Department of Mathematics and Computer Science
Western Connecticut State University
181 White Street
Danbury, CT 06810

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