[Orca-users] Question regarding Statistical Calculations...

[David Michaels]

Sanford, Klaus G. wrote:

> Dear Sir or Ma'am,
>
>  
>
>   _What is the statistical definition and value of taking the minimum 
> and maximum values in a data set and taking their average._
>
>  
>
> (e.g.  sample size=30 ;  min =8  ; max =79 ; take avg = 8+79 / 2 = 43.5)
>
>  
>
>   So 43.5 is the avg of the max and min value but what is the term for 
> this calculation?  Thanks.
>

I don't think the average of a min and max value has any stastical 
significance whatsoever.  Perhaps it would be termed the "midpoint" or 
somesuch.  But I'm not sure what context you're asking this in -- is 
there something in Orca that relates to your question?  Many orca graphs 
list a "min, average, max" tuple of data for a particular object, but 
the 'average' isn't necessarily the average formula you cite above.  The 
average is calculated over the timescale of the graph in question.  It 
could be an hour, a day, a week, a month, a quarter, or a year.

For example, look at this graph:

The image

As you can see, it's a weekly graph.  Look at the big spike in disk 
activity on Wednesday, around noon (interesting corresponding spike in 
network activity - someone was probably streaming some big data file 
across NFS).  Even though the 'max' for this graph for Disk is 4000, and 
the min is 0, note that the average is /not/ 2000, but 238.

I'm not positive, but I believe this average is just that -- a 
statistical average.  The sum of values divided by the quantity of 
values.  There are plenty of other statistical evaluations you can 
impose and present in the graph, such as mean, standard deviation, 
variance, etc.  Maybe put that on the slate of discussion for Orca 3.0. ;)

--Dragon

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