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Subject: Standard deviations -- how many games?

Author: Dann Corbit

Date: 12:24:31 01/23/04


30 experiments is a fairly standard rule as to when you should start to trust
the results for experimental data.

From:
http://www.twoplustwo.com/mmessay8.html
"A good rule of thumb is to have at least 30 observations (playing sessions) for
the estimate to be reasonably accurate. However, the more the better, unless for
some reason you think the game for which you are trying to estimate your
standard deviation has changed significantly over some particular period of
time."

From:
http://www.odu.edu/sci/xu/chapter3.pdf
"C. The Reliability of s as a Measure of Precision - the more measurements that
are made, the more reliable the value obtained for s. Usually 20 - 30
measurements are necessary."

From
http://www.stat.psu.edu/~resources/ClassNotes/ljs_21/ljs_21.PPT#11
Concerning the central limit theorem, we have this:
Even if data are not normally distributed, as long as you take “large enough”
samples, the sample averages will at least be approximately normally
distributed.
Mean of sample averages is still mu
Standard error of sample averages is still sigma/sqrt(n).
In general, “large enough” means more than 30 measurements.


Of course, the more the merrier, when it comes to measurements.



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