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Science Forum Index » Statistics - Education Forum » question about use of poisson probabilities
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| Dora Smith |
 Posted: Sat Feb 03, 2007 11:10 pm |
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Guest
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I work for a firm that compiles a database of license plate numbers, some of
which correspond to cars that flunk roadside emissions testing. We
process on the average 617,000 records a month, about 30% of which (more or
less) meet various criteria of our contract.
My boss has me using Excel to compute graphs, charts and statistics on our
data. I know Excel and have basic knowledge of statistics adn regression,
but am not familiar with everything he has asked for.
My boss specifically wants me to give him poisson probabilities of meeting
our goals.
I am having two problems, and I don't know if you can help me with computing
Poisson probabilities with Excel or not, but since when I use Excel to do
Poisson probability examples on the Web I get the correct answers, I suspect
this part of my problem is related to the main question I have for you.
When I tried to use an online Poisson computer, it told me my numbers were
far too large!
The way I am understanding Poisson probabilities, they are used to compute
probabilities of very small, discrete numbers of things occurring, given
only the mean number of occurrences in some unit, like an hour, a day, or
five pages of typing. The formua for a Poisson probability clearly tells
me why a computer with limited resources might have trouble if the mean is
617,000, particularly if you want a cumulative probability. I am getting
the idea that poisson probabilities are used to track traffic, but the sort
of problems they are applied to is how many cars will run a light in an
hour. If he wants to computer how many cars will pass his van in an hour
on a particular highway then a Poisson probability might prove useful.
Are poisson probabilities applicable to my application? Can they be
successfully computed for large numbers?
If not, can you just suggest what statistics might be helpful for my boss's
forecasting. Frankly, what my boss says he wants to know sounds more like
goal seeking - but he insists he specifically wants poisson probabilities.
Thanks!
Yours,
Dora Smith
Austin, TX
tiggernut24@yahoo.com
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Yours,
Dora Smith
Austin, TX
tiggernut24@yahoo.com |
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