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Re: st: Average of Sample vesus Sub-Samples


From   Jeph Herrin <junk@spandrel.net>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Average of Sample vesus Sub-Samples
Date   Fri, 19 Mar 2010 09:49:54 -0400

Yes, if they are negative.


 A = -1,-1,-1
 B = -3
then
 mean(A) = -1
 mean(B) = -3
 (mean(A)+mean(B))/2 = -2
 mean(A+B)= -6/4 = -1.5

-1.5 > -2

So the average of all 4 numbers is larger than
the average of the means of the two subsamples.


hth,
Jeph





Erasmo Giambona wrote:
Dear Statalisters,

Is it possible that the arithmetic average of a sample is larger than
the averages of two sub-samples containing overall all the
observations of the full samples?

Any thoughts would be appreciated,

Erasmo
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