"Glen Barnett" <[EMAIL PROTECTED]> wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> Chia C Chong wrote:
> >
> > Thanks for your advice Glen.
> >
>
> No worries. If you still need to do some kind of goodness
> of fit test the first step is to discuss the alternatives
> of interest.
>
> Glen
It is certainly true that the procedure you choose must depend on the
alternative hypotheses of interest. If the alternatives are characterised by
over-dispersion or under dispersion, a specific goodness of fit test which
does not involve loss of information by grouping data uses R A Fisher's
"dispersion test"
X^2 = (sum of [(x(i) - xbar)^2])
/xbar ,
which is distributed, for a Poisson variate as a Chi squared
variable on n-1 degrees of freedom.
If the alternative of interest is over-dispersed , the rejection region
would be the upper tail of the Chisquare distribution and vice-versa.
Unfortunately, the reference I have to this is a very old one.-Cochran,
W.G., Biometrics,1954, quoted in my very old edition of Kendall and Stuart,
Advanced Theory of Statistics, volume 2 .
.
.
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