
   I´m not an expert either, but from my own experience with those annoying 
messages, I can suggest you some precautions you should take:

   - First of all, make sure, in your ".txt" file, that you are using dots for 
separating decimals, NOT commas. 

   - Before writing your model, test each of the variables you are using (just 
type the name) and check that the software has not interpreted any covariate as 
a factor or viceversa.

   Hope that helps a bit. 

   Good luck.
   
   




________________________________
De: Sophie Higgins <england116@hotmail.com>
Para: hugo.mildenberger@web.de; r-help@r-project.org; 
r-sig-mixed-models@r-project.org
Enviado: dom,26 junio, 2011 13:26
Asunto: Re: [R-sig-ME] [R] Help with lmer


Hello Hugo,
Thank you for your reply.  
This is a snap shot of what my data looks like:







  Presencebsence
  Habitatype
  Substratetype
  Width
  Banktype
  BankIncline
  Bankheight
  Waterdepth


  0
  Lake
  Rocksgravel
  600
  Earth
  0.45
  less1
  greater2


  0
  Lake
  Rocksgravel
  600
  Earth
  0.45
  less1
  greater2


  1
  Lake
  Rocksgravel
  600
  Earth
  0.45
  less1
  greater2


  0
  Lake
  Rocksgravel
  600
  Earth
  0.45
  less1
  greater2


  0
  Lake
  Rocksgravel
  600
  Earth
  0.45
  less1
  greater2


  0
  Stream
  Rocksgravel
  1
  Rocks
  0.45
  less1
  025to05


  0
  Stream
  Rocksgravel
  1
  Rocks
  0.45
  less1
  025to05


  0
  Stream
  Rocksgravel
  1
  Rocks
  0.45
  less1
  025to05


  0



  Stream
  Rocksgravel
  1
  Rocks
  0.45
  less1
  025to05


  









  







I am trying to find out if any off the above factors so substrate type, width, 
bank type etc have an effect on the presence/absence of the species in 
question.  But as stated below I keep getting an error message up and I have no 
idea how to fix it in order for me to fun the lmer.
Sophie 
> From: Hugo.Mildenberger@web.de
> To: r-help@r-project.org
> CC: england116@hotmail.com
> Subject: Re: [R] Help with lmer
> Date: Fri, 24 Jun 2011 17:19:00 +0200
> 
> Sophie,
> 
> I'm myself quite new to linear mixed effect models, but "PresenceAbsence"
>sounds like
> a binary response variable. So  wouldn't be
> 
>      m1<-lmer(Presencebsence~Habitatype*Width+(1|Sitename),familiy=binomial)
> 
> the first thing to try?  There is also a special mailing list for linear - 
>mixed -effect 
>
> models:
> 
>      r-sig-mixed-models@r-project.org
> 
> But with numeric problems like this one you really should provide a self
>contained 
>
> example (i.e. with data),  at least the output of str(yourdata), if ever
>possible. 
>
> 
> Kind regards
> 
> Hugo
> 
> On Friday 24 June 2011 13:11:23 Sophie Higgins wrote:
> > 
> > Hey,
> > I am having trouble with lmer.  I am looking at the presence/absence of water 
>shrews against habitat and other factors e.g
> > so I used this:
> > m1<-lmer(Presencebsence~Habitatype*Width+(1|Sitename))summary(m1)
> > But i keep getting this error up
> > Error in mer_finalize(ans) : Downdated X'X is not positive definite, 16.> 
>summary(m1)Error in asMethod(object) : matrix is not symmetric [1,2]
> > What does this mean and now can I fix it?
> > Sophie                           
> >     [[alternative HTML version deleted]]
> > 
> > ______________________________________________
> > R-help@r-project.org mailing list
> > 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-sig-mixed-models@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models

	[[alternative HTML version deleted]]

