Re: pspp-dev Digest, Vol 161, Issue 12

[John Darrington]

On Sat, Jun 10, 2017 at 02:14:11PM +0300, Elias Estatistics wrote:
     What means "Mean Average" inside aggregated menu (selections)?
     
     Can you explain me in order to translate it properly?
     I can find any relevant reference about that math phrase

There are various types of average:


Median Average: 
   This is the value which half of the samples fall above and half fall below.
   Eg: the median of 1 2 3000000  = 2

Mode Average: 
   This is the value which more samples have, than any other value.
   Eg: the mode of 1 2 3 3 3 78   = 3

Mean Average: Sometimes called the "Pythagorean Mean" [1]
   There are in fact (at least) 3 different  types of "Mean Average", however
   the term usually refers to the "Arithmetic Mean Average" unless the context
   makes otherwise clear:

Arithmetic Mean Average: (\sum_{i=0}^{n-1} x_i ) / n

        Eg: Arithmetic Mean of 1 2 3000000 = 1000001

Geometric Mean Average: (\prod_{i=0}^{n-1} x_i ) ^ {1/n}

        Eg: Geometric Mean of 1 2 3000000 = 181.711 (approx)

Harmonic Mean Average:  n / (\sum_{i=0}^{n-1} 1/x_i )

        Eg: Harmonic Mean of 3 4 5 = 3.829 (approx)


Hope this helps,

John





[1] https://en.wikipedia.org/wiki/Pythagorean_means



(Like the wikipedia article says, the Greeks have studied the subject in great 
depth!)



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