[R] model non-integer count outcomes

[Wensui Liu]

Thanks Thierry
What if I don't know the n in the offset term?

On Wednesday, July 22, 2015, Thierry Onkelinx <thierry.onkelinx at inbo.be>
wrote:

> If you know the number of counts (n) used to calculate the average then you
> can still use a poisson distribution.
>
> Total = average * n
> glm(total ~ offset(n), family = poisson)
>
> ​
> ir. Thierry Onkelinx
> Instituut voor natuur- en bosonderzoek / Research Institute for Nature and
> Forest
> team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
> Kliniekstraat 25
> 1070 Anderlecht
> Belgium
>
> To call in the statistician after the experiment is done may be no more
> than asking him to perform a post-mortem examination: he may be able to say
> what the experiment died of. ~ Sir Ronald Aylmer Fisher
> The plural of anecdote is not data. ~ Roger Brinner
> The combination of some data and an aching desire for an answer does not
> ensure that a reasonable answer can be extracted from a given body of data.
> ~ John Tukey
> Op 22 jul. 2015 08:38 schreef "Don McKenzie" <dmck at u.washington.edu
> <javascript:;>>:
>
> > Or if there are enough averages of enough counts, the CLT provides
> another
> > option.
> >
> > > On Jul 21, 2015, at 8:38 PM, David Winsemius <dwinsemius at comcast.net
> <javascript:;>>
> > wrote:
> > >
> > >
> > > On Jul 21, 2015, at 8:21 PM, Wensui Liu wrote:
> > >
> > >> Dear Lister
> > >> When the count outcomes are integers, we could use either Poisson or
> > >> NB regression to model them. However, there are cases that the count
> > >> outcomes are non-integers, e.g. average counts.
> > >> I am wondering if it still makes sense to use Poisson or NB regression
> > >> to model these non-integer outcomes.
> > >
> > > There is a quasi-binomial error model that accepts non-integer
> outcomes.
> > >
> > > --
> > >
> > > David Winsemius
> > > Alameda, CA, USA
> > >
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> >
> >
> >
> > ______________________________________________
> > R-help at r-project.org <javascript:;> mailing list -- To UNSUBSCRIBE and
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> > and provide commented, minimal, self-contained, reproducible code.
> >
>
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>
> ______________________________________________
> R-help at r-project.org <javascript:;> mailing list -- To UNSUBSCRIBE and
> more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.



-- 
WenSui Liu
https://statcompute.wordpress.com/

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