how to test poisson distribution

To be pedantic (I'm feeling cranky today):

One can never test "whether the data follow ["data" is plural] a
Poisson distribution" -- only whether there is sufficient evidence to
cast that assumption into doubt. Perhaps a better shorthand is
"whether the data are consistent with Poisonness" . This correctly
leaves open the possibility that the data are consistent with lots of
other distribution-nesses, too. I welcome alternatives, perhaps
privately to reduce the list noise level.
...now that Berton mentioned `checking distribution-nesses': the
function distplot() in the package vcd implements various plots for
distribution-nesses that can be used for graphical checking. Ord_plot()
is made for a similar purpose.
Finally, there is also a function goodfit() that computes
goodness-of-fit tests for such hypotheses.

All three functions are written following Chapter 2 `Fitting and
Graphing Discrete Distributions' in Michael Friendly's book `Visualizing
Categorical Data'.

hth,
Z
(And,yes, I'm sure that Thomas knows this perfectly well).

I do think that we should be a bit less sloppy about such things even
here, lest we continue to promulgate already widespread
misunderstandings, even at the cost of slightly increased bandwidth.
After all, precision is supposed to be a major concern or ours.

As I've been cranky, others are free to return the favor. Sauce for
the goose ...

-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA

"The business of the statistician is to catalyze the scientific
learning process."  - George E. P. Box

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch 
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Thomas 
Sch??nhoff
Sent: Wednesday, October 19, 2005 10:00 AM
To: r-help at stat.math.ethz.ch
Subject: Re: [R] how to test poisson distribution

Hi,

2005/10/19, Wensui Liu <liuwensui at gmail.com>:
Dear All,

I am wonderng how to test whether the data follows poisson 
distribution.
Thank you so much!
Did you notice the PDF on distribution tests using R by Vito Ricci,
its found at CRAN in the docs contrib section, called "FITTING
DISTRIBUTIONS WITH R"

Maybe this could be of some help for you, especially look at page 7
(poisson dsitribution example).

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how to test poisson distribution

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