You missed the point entirely. You should have looked at the original
message.

"Harlan Grove" wrote in message
...
"Dave Thomas" wrote...
Actually the average would be 100, but your point is well taken. You can
have a mixture of positive and negative with no zeroes.
...

Actually the example completely misses the point. It'd be necessary to use
the column containing profit or loss in order to change signs. And the
lovely example provides a very nearly meaningless average - cumulative
return divided by number of periods is +100, but 2 out of 3 periods
generated negatives.

Further, there are no zeros. If there are no zeros, then just use AVERAGE.
If, however, there are zeros, e.g.,

Month 1 100 loss
Month 2 100 loss
Month 3 500 profit
Month 4 0 no return
Month 5 0 no return

is the average monthly return still 100 or is it now 60?

This has everything to do with real world processes. Averages of all
negatives, or averages of all positives, or averages of all numbers
(positive, negative AND zero) make sense. Averages of positives and
negatives but not zero never make sense.