[R] Dealing with heterogeneity with varComb weights

2009-09-17 Thread RS27

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))

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


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Re: [R] Dealing with heterogeneity with varComb weights

2009-09-17 Thread 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: highs...@highstat.com
URL: www.highstat.com



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