[R] Help with lmer

[Hugo Mildenberger]

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 at 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]]
> 
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