Hi everyone,

 

I'm trying to use function vcov to extract the covariance matrix from a
GAMLSS object. But I'm getting some strange errors and I was hoping someone
could help me out? Vcov works with the same model for lm and glm objects,
but not gamlss objects. I've searched various help sites to no avail.

 

Its very possible the reason is that vcov failed though, since I got the
following error message in the summary of the model  "summary: vcov has
failed, option qr is used instead"

 

In which case I was wondering if anyone could help me out by explaining how
I can find the covariance matrix equivalent without using vcov? 

 

 

The code and error messages I got for vcov are as follows.

> vcov(paper_size_type_income)

 

        The following object(s) are masked _by_ .GlobalEnv :

 

         child id paper 

 

Error in gamlssNonLinear(family = RG, data = paper3, y = paper, mu.formula =
paper ~  : 

  NAs in y - use na.omit()

 

I then try using na.omit and I get a different error message (even though
there are no NA's in the data set, I checked using table(paper3$paper,
exclude=NULL))

 

> temp <- gamlss(na.omit(paper)~size + type + income, family=RG,
data=paper3)

GAMLSS-RS iteration 1: Global Deviance = 1160.816 

GAMLSS-RS iteration 2: Global Deviance = 1159.963 

GAMLSS-RS iteration 3: Global Deviance = 1159.951 

GAMLSS-RS iteration 4: Global Deviance = 1159.951 

> vcov(temp)

 

        The following object(s) are masked _by_ .GlobalEnv :

 

         child id paper 

 

Error in inteprFormula.default(formula, .envir = envir, .start = start.v,  :


  covariates in formulae with unknowns must not be factors

check sizecovariates in formulae with unknowns must not be factors

check typecovariates in formulae with unknowns must not be factors

check income

> 

 

 

thanks

 

 

 

 

 

Chris Howden

Marketing Scientist

For all your Analysis, Modelling, Experimental Design and Training needs

(mobile) 0410 689 945

(fax / office) (+618) 8952 7878

tall.chriss@yahoo.com.au

 


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