Nested fixed factors in glmer: Error in mer_finalize(ans) : Downdated X'X is not positive definite, 1.

Hi Hugo,

Thanks for your e-mails. The structure of my data is not the one in  
your examples but:

Factor 1: a,b,c
factor 2: 1,2,3,4,5,6

combination:
a.1, a.2, b.3, b.4, c.5, c.6

note factor 2 is nested within factor 1, so that not all levels of  
factor 2 are in every level of factor 1.
Hence I do not have a full factorial or crossed design but a hierarchical one.

My question: How can I include such a design in glmer?

Cheers,

Sara

Hugo.Mildenberger at web.de escribi?:

On Thu, 28 Feb 2013 14:27:36 +0100
"PALACIO BLASCO, SARA" <s.palacio at ipe.csic.es> wrote:

Maybe this is a trivial question but: how can I specify a nested
structured of fixed factors in glmer?

I still haven't found a way to solve the issues explained in my
previous e-mail.

Sara,

may be this fits your needs?

a<-factor(c('a','b','c','d'))
b<-factor(c('1','2'))
interaction(a,b)

[1] a.1 b.2 c.1 d.2
Levels: a.1 b.1 c.1 d.1 a.2 b.2 c.2 d.2


Best