Dear Emma,

Have you tried a simpler model? False convergence can be due to an
overcomplex model. Can you give a brief outline of your data? E.g. how
many sites, how many data per site, ... Cross tabulations of all pairs
of factor variables are usefull too.

HTH,

Thierry 


------------------------------------------------------------------------
----
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.onkel...@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: Emma Stone [mailto:emma.st...@bristol.ac.uk] 
Verzonden: vrijdag 13 maart 2009 10:50
Aan: ONKELINX, Thierry; Emma Stone; r-help@r-project.org
Onderwerp: RE: [R] Mixed models fixed effects

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??

Emma


--On 11 March 2009 15:45 +0100 "ONKELINX, Thierry" 
<thierry.onkel...@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.onkel...@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-boun...@r-project.org
[mailto:r-help-boun...@r-project.org]
> Namens Emma Stone
> Verzonden: woensdag 11 maart 2009 15:29
> Aan: r-help@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.st...@bristol.ac.uk



Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver weer 
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and any annex are purely those of the writer and may not be regarded as stating 
an official position of INBO, as long as the message is not confirmed by a duly 
signed document.

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