ASokolik wrote...
Clearly if all I really wanted to do was calculate for myself the RSD of a
few numbers, I wouldn't be going to such great lengths to write a program for
it. I work with some people that aren't quite as adept with Excel or with
statistics or with algebraic manipulation, so to tell them to make a
spreadsheet and calculate the RSD of some numbers typically causes more work
for me than simply doing it myself.

I was hoping to be able to write a "quick" program that I could install as
an add-in on their machines so they could just type =RSD(cells) instead of

=stdev(cells)/average(cells)*100
....

Give these other people a template file. Put a clear entry range in it.
Best to use a different background color, and borders don't hurt
either. Then put the formula

=100*STDEV(range)/AVERAGE(range)

in a prominent place near the entry range. All they'd need to do is
enter the numbers, and your template would give them the descriptive
statistics.

While giving them a udf to use rather than two built-in functions in a
3-term formula may reduce the support headache somewhat, you'll have
the pleasure of different support headaches if any of these other users
have macro security set to High.

Also, as I already mentioned, Excel can evaluate

=100*STDEV(Sheet1:Sheet100!A1:Z2000)/AVERAGE(Sheet1:Sheet100!A1:Z2000)

There's no clean way to use 3D references with your udf that wouldn't
introduce greater complications than telling them to use built-in
functions.