My boss wants me to use poisson probabilities to compute the liklihood of
meeting various goals in relation to our project, where the average number
of records per month is 617,000.

I am having trouble getting Excel to compute probabilities as other than 0
or 1, though when I do examples on the web that involve very small numbers I
get teh correct answers with no trouble.

Are poisson probabilities intended for this use? Or are they only
applicable for small numbers of discrete events, like the liklihood that 4
cars will run a traffic light in a day?

What would be the appropriate statistic for the probability of meeting a
goal of 700,000 discrete events in a month, or a few million in a year?

--
Yours,
Dora Smith
Austin, TX




--
Yours,
Dora Smith
Austin, TX

Hello, Dora!
You wrote on Sun, 4 Feb 2007 08:52:38 -0600:

DS I am having trouble getting Excel to compute probabilities
DS as other than 0 or 1, though when I do examples on the web
DS that involve very small numbers I get teh correct answers
DS with no trouble.

DS Are poisson probabilities intended for this use? Or are
DS they only applicable for small numbers of discrete events,
DS like the liklihood that 4 cars will run a traffic light in
DS a day?

DS What would be the appropriate statistic for the probability
DS of meeting a goal of 700,000 discrete events in a month, or
DS a few million in a year?

Technically, I think Poisson statistics are correct but, for
such large numbers of events, normal statistics should produce
similar probabilities.

James Silverton
Potomac, Maryland

E-mail, with obvious alterations:
not.jim.silverton.at.comcast.not

James, my knowledge of probability theory is weak, and I'm no mathematical
theorist.

What do you mean by poisson and normal statistics? I know of only one
poisson statistic - the poisson probability that Excel computes with the
Poisson function. Are there more poisson statistics, how do I learn of
them, and does Excel compute them?

What are you talking about by normal statistics? Plain ol' regression and
analysis of variance? I think that stuff is based on the normal curve.

One thing - the numbers may be large, but the number of months, ie, data
points, that we are basing conclusions about probability of achieving our
goals on is small. Only 27 months. Does that make a difference?

--
Yours,
Dora Smith
Austin, TX


"James Silverton" wrote in message
...
Hello, Dora!
You wrote on Sun, 4 Feb 2007 08:52:38 -0600:

DS I am having trouble getting Excel to compute probabilities
DS as other than 0 or 1, though when I do examples on the web
DS that involve very small numbers I get teh correct answers
DS with no trouble.

DS Are poisson probabilities intended for this use? Or are
DS they only applicable for small numbers of discrete events,
DS like the liklihood that 4 cars will run a traffic light in
DS a day?

DS What would be the appropriate statistic for the probability
DS of meeting a goal of 700,000 discrete events in a month, or
DS a few million in a year?

Technically, I think Poisson statistics are correct but, for such large
numbers of events, normal statistics should produce similar probabilities.

James Silverton
Potomac, Maryland

E-mail, with obvious alterations: not.jim.silverton.at.comcast.not

Hello, Dora!
You wrote on Sun, 4 Feb 2007 12:08:17 -0600:

DS What do you mean by poisson and normal statistics? I know

It's simple enough Poisson statistics converge towards Gaussian
when the numbers are large enough.

James Silverton
Potomac, Maryland

E-mail, with obvious alterations:
not.jim.silverton.at.comcast.not

why don't u try

http://www.ytnow.com/probability/mat...%20probability

-via135

On Feb 4, 7:52 pm, "Dora Smith" wrote:
My boss wants me to use poisson probabilities to compute the liklihood of
meeting various goals in relation to our project, where the average number
of records per month is 617,000.

I am having trouble getting Excel to compute probabilities as other than 0
or 1, though when I do examples on the web that involve very small numbers I
get teh correct answers with no trouble.

Are poisson probabilities intended for this use? Or are they only
applicable for small numbers of discrete events, like the liklihood that 4
cars will run a traffic light in a day?

What would be the appropriate statistic for the probability of meeting a
goal of 700,000 discrete events in a month, or a few million in a year?

--
Yours,
Dora Smith
Austin, TX


--
Yours,
Dora Smith
Austin, TX