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> 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 > > ______________________________________________ > R-help at r-project.org 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.
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>:> 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> > 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 > > > > ______________________________________________ > > R-help at r-project.org 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. > > > > ______________________________________________ > R-help at r-project.org 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. >[[alternative HTML version deleted]]
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 > > > > > > ______________________________________________ > > > 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. > > > > > > > > ______________________________________________ > > 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. > > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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/ [[alternative HTML version deleted]]