[R-sig-ME] glm question

[Ken Beath]

The way your data is setup for prediction as grass height varies so do the
other two predictors so the prediction reflects ht is happening in all the
covariates.

Hold the other two constant as you change grass height. What is usually
done is to do this for a series of values of the other predictors and plot
the multiple curves.


Ken

On 20 August 2015 at 01:47, Joaquín Aldabe <joaquin.aldabe at gmail.com> wrote:

> Thanks Thierry, I´ve attached the data in excel format and the script in
> txt. I´ll also write to r-help.
> Best wishes,
> Joaquín.
>
> 2015-08-19 11:54 GMT-03:00 Thierry Onkelinx <thierry.onkelinx at inbo.be>:
>
> > Dear Joaquin,
> >
> > Your attachments got stripped. It's better to put them somewhere on
> > line an add a link in your message.
> >
> > If your problem concerns a glm() then r-help would be a better mailing
> > list. If it is about glmer() then this mailing list is fine.
> >
> > Best regards,
> > 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
> >
> >
> > 2015-08-19 16:39 GMT+02:00 Joaquín Aldabe <joaquin.aldabe at gmail.com>:
> > > Dear All, I´m running a glm with poisson errors and have a doubt when
> > > ploting the predicted values. One of my variables has a positive slope
> in
> > > the summary output, but when I plot the predicted values on the
> original
> > > plot it draws a line with negative slope. I appreciate your comments on
> > > this and any other aspect of the analysis.
> > >
> > > Attached is the script and data.
> > >
> > > Thanks in advanced,
> > >
> > > Joaquín.
> > >
> > > pd. If this is not the correct forum to ask about glm, please let me
> > know.
> > >
> > > --
> > > *Joaquín Aldabe*
> > >
> > > *Grupo Biodiversidad, Ambiente y Sociedad*
> > > Centro Universitario de la Región Este, Universidad de la República
> > > Ruta 15 (y Ruta 9), Km 28.500, Departamento de Rocha
> > >
> > > *Departamento de Conservación*
> > > Aves Uruguay
> > > BirdLife International
> > > Canelones 1164, Montevideo
> > >
> > > https://sites.google.com/site/joaquin.aldabe
> > > <https://sites.google.com/site/perfilprofesionaljoaquinaldabe>
> > > _______________________________________________
> > > R-sig-mixed-models at r-project.org mailing list
> > > https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
> >
>
>
>
> --
> *Joaquín Aldabe*
>
> *Grupo Biodiversidad, Ambiente y Sociedad*
> Centro Universitario de la Región Este, Universidad de la República
> Ruta 15 (y Ruta 9), Km 28.500, Departamento de Rocha
>
> *Departamento de Conservación*
> Aves Uruguay
> BirdLife International
> Canelones 1164, Montevideo
>
> https://sites.google.com/site/joaquin.aldabe
> <https://sites.google.com/site/perfilprofesionaljoaquinaldabe>
>
> _______________________________________________
> R-sig-mixed-models at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
>
>


-- 

*Ken Beath*
Lecturer
Statistics Department
MACQUARIE UNIVERSITY NSW 2109, Australia

Phone: +61 (0)2 9850 8516

Level 2, AHH
http://stat.mq.edu.au/our_staff/staff_-_alphabetical/staff/beath,_ken/

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