Dora -

Disregard my reply.

It seems you started a new thread instead of continuing your original
thread, and I didn't realize you are working with an extreme situation where
there may be problems using Excel's built-in functions.

- Mike

"Mike Middleton" wrote in message
...
Dora -

... is there a way to plug a level of probability you want to achieve
in and have it give you the number of records one has a 99% probability
of achieving? <

I think that's what the POISSON worksheet function does when you set the
third argument (cumulative) equal to TRUE.

- Mike
http://www.mikemiddleton.com

"Dora Smith" wrote in message
...
OK, I understand why it makes more sense to use the normal distribution,
on our hundreds of thousands of records, but my boss is not convinced -
mabye because he knows the Poisson distribution is skewed to the left,
and he said something about getting higher probabilities than 97%. I
dunno. Maybe the purpose has to do with improving performance.

My question now is, can Excel generate one-tailed confidence intervals
for the Poisson distribution? In other words, is there a way to plug
a level of probability you want to achieve in and have it give you the
number of records one has a 99% probability of achieving?

If not, what plugins for Excel are available to accomplish that - without
needing to know visual basic or something to use them?

I have an idea not, but I'm double checking.

--
Yours,
Dora Smith
Austin, TX