[R] Dealing with heterogeneity with varComb weights

[Alain Zuur]

RS27 wrote:
> 
> Hi,
> I am trying to add multiple variance structures such as the first example
> below:
> 
> vf1 <- varComb(varIdent(form = ~1|Sex), varPower())
> 
> However my code below will not work can anybody please advise me?
> 
> VFcomb<-varComb(varExp(form=~depcptwithextybf),varFixed(form=~FebNAO))
> 
> 
> 
> VarFixed won't work if FebNAO has values equal to 0. In fact, I wouldn't
> use varFixed at all. 
> 
> 
> A bit more info on the error message would be handy...
> 
> Alain
> 
> 
> also if you have two variables with the same weights function would you
> write that as:
> 
> VFcomb<-varComb(varExp(form=~depcptwithextybf),varExp(form=~FebNAO))
> 
> thanks
> Rebecca
> 
> 
> 


-----
--------------------------------------------------------------------
Dr. Alain F. Zuur
First author of:

1. Analysing Ecological Data (2007).
Zuur, AF, Ieno, EN and Smith, GM. Springer. 680 p.

2. Mixed effects models and extensions in ecology with R. (2009).
Zuur, AF, Ieno, EN, Walker, N, Saveliev, AA, and Smith, GM. Springer.

3. A Beginner's Guide to R (2009).
Zuur, AF, Ieno, EN, Meesters, EHWG. Springer


Statistical consultancy, courses, data analysis and software
Highland Statistics Ltd.
6 Laverock road
UK - AB41 6FN Newburgh
Email: highstat at highstat.com
URL: www.highstat.com



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