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# Re: st: Average of Sample vesus Sub-Samples

 From Jeph Herrin 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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