[R] Mixed models fixed effects

Emma Stone Emma.Stone at bristol.ac.uk
Fri Mar 13 10:49:39 CET 2009

Hi Thierry,

That's great thanks!

I have done as you have said but I keep getting a warning message here is 
my code:

G1Hvol<-glmer(passes~hvolume+style+habitat(1|Site),family = poisson)

And this is the message i get:
Warning message:
In mer_finalize(ans) : false convergence (8)

any ideas??


--On 11 March 2009 15:45 +0100 "ONKELINX, Thierry" 
<Thierry.ONKELINX at inbo.be> wrote:

> Hi Emma,
> Continuous predictors are no problem at all. You can mix both continuous
> and categorial predictors if needed. I suppose your response are counts
> (the number of bats that passes)? In that case a generalised linear
> mixed model is more appropriate. With the lme4 package you could try
> something like this:
> library(lme4)
> Model <- glmer(BatPasses ~ Width + Height + (1|Site), family = poisson)
> HTH,
> Thierry
> PS There is a mailing list dedicated to mixed models: R-Sig-MixedModels
> ------------------------------------------------------------------------
> ----
> ir. Thierry Onkelinx
> Instituut voor natuur- en bosonderzoek / Research Institute for Nature
> and Forest
> Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,
> methodology and quality assurance
> Gaverstraat 4
> 9500 Geraardsbergen
> Belgium
> tel. + 32 54/436 185
> Thierry.Onkelinx at inbo.be
> www.inbo.be
> 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
> -----Oorspronkelijk bericht-----
> Van: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
> Namens Emma Stone
> Verzonden: woensdag 11 maart 2009 15:29
> Aan: r-help at r-project.org
> Onderwerp: Re: [R] Mixed models fixed effects
> Dear All,
> This may sound like a dumb question but I am trying to use a mixed model
> to
> determine the predictors of bat activity along hedges within 8 sites. So
> my
> response is continuous (bat passes) my predictors fixed effects are
> continuous (height metres), width (metres) etc and the random effect is
> site  - can you tell me if the fixed effects can be continuous as all
> the
> examples I have read show them as categorical, but this is not covered
> in
> any documents I can find.
> Help!
> Emma
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Emma Stone
Postgraduate Researcher
Bat Ecology and Bioacoustics Lab
& Mammal Research Unit
School of Biological Sciences,
University of Bristol, Woodland Road,
Bristol, BS8 1UG
Email: emma.stone at bristol.ac.uk

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