PivotTable canned functions
 

I am using Excel 2000 (9.0.2720).

In my work I often faced with the task of creating ratios of
CurrentListValue / CurrentSaleValue then need to perform various
calculations on those ratios to identify and conclude on Central Tendencies
(among other things) within categories from a parent array. The list of
functions available for PivotTable calculation (I am assuming under the hood
these are Array Functions) is very narrow. Only providing for Average,
Standard Deviation, Min, Max, etc.

Is there a way to add to this list, such as but not limited to, Average
Deviation, Median, Geometric Mean, Harmonic Mean and a whole host of other
statistical functions working upon a list? I spend hours, even days at a
time rendering these results by hand for given periods of time. Example: I
break down years of data into internal periods of time (term) whether they
be BiAnnual, Quarterly, Monthly or some combination of those to produce the
following:

Calculation on list of individual ratios from a particular geographic area
and/or class of items from a parent array using ArrayFunctions...
Area = 1; Class = 4; Term = Quarter
Term Count Average Median G.Mean H.Mean AveDev Stdev
1 15 .75 .## .## .## .##
..##
2 22 .84 .## .## .## .##
..##
3 16 .92 .## .## .## .##
..##
4 20 1.00 .## .## .## .##
..##

etc, etc, etc. Charting the results for purposes of further study:
regression, trending, etc.

It seems that a PivotTable would be ideal for this type of process and
without parsing individual categories of items from the parent array by
hand.

Hope this makes sense...

TIA