Re: clarify or clogify? re: Why the human race is growing apart

On Fri, 10 Apr 2009 09:25:26 -0700 (PDT), tgdenning@xxxxxxxxxxxxx
wrote:

On Apr 10, 12:02=A0pm, c...@xxxxxxxx (Richard Harter) wrote:
On Fri, 10 Apr 2009 03:44:54 -0700 (PDT), tgdenn...@xxxxxxxxxxxxx
wrote:

1) We are selecting from the set of integers which represents the
range of scores of the entire population that has taken the test.

2) We are not selecting group average scores at random, but from real
data. If we were to divide the population at random into two groups,
for example, the probability would be *extremely high* that the
average of the scores would be identical.

I gather that statistics works differently on your planet.

I guess neither of you guys can refute my claim using statistics,
otherwise you would have.

The trouble is that you are arrogant, ignorant, and
condescending. Try to get it down to two out of three.

That said, the probability that the average of the score would be
identical is quite small. Briefly, the two averages can only be
identical if the sums of all the scores in each sub group is
exactly the same. This is possible because all of the individual
scores are integers. It is quite unlikely. Think about it this
way. Suppose there is some arrangement such each half has the
same identical average. Then swapping any two people with
different IQ's from one group to the other will change the
average from identical to not identical. On the other hand if
the selection is such that the two averages are not identical,
swapping two individuals at random is not likely to make the
averages identical. In short, there are many more ways for the
average not to beidentical than to be identical.

In actual fact we can use standard statistical theory to estimate
how far apart the two averages are likely to be. The standard
deviation of the mean of a sample is the population mean divided
by the square root of the sample size. If the population mean is
100 and the standard deviation is 10, and the sample size is
1,000,000 the then the sample mean standard deviation is .01.

Quite simply, if the population size is large, the difference in
means between the two halves will be small, but it won't be zero.


Richard Harter, cri@xxxxxxxx
http://home.tiac.net/~cri, http://www.varinoma.com
If I do not see as far as others, it is because
I stand in the footprints of giants.

.

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