[R-sig-eco] Error in solve.default(as.matrix(fit$hessian))

[Gavin Simpson]

On Mon, 2010-02-22 at 08:06 +0100, Roman Luštrik wrote:
> Dear list,
> 
> I'm trying to construct a zero-inflated negative binomial model but I get
> greeted by an error. I haven't had the chance to try my dataset on different
> OSs or different R version, but I did mange to try that for the "cod
> parasite" data from Zuur et al book (Mixed effect models...) and I get a
> similar error (models with different formulas may or may not go through,
> depending on R  version and the system). This is the error I get for the cod
> data.
> 
> 1> nb1a <- zeroinfl(Intensity ~ Area*Year | Area*Year + Length,
> dist="negbin", link="logit", data=ParasiteCod2)
> Error in solve.default(as.matrix(fit$hessian)) :
>   system is computationally singular: reciprocal condition number =
> 1.5208e-17
> 
> I get the same error on my data:
> 
> frm <- formula(st_zir ~ obs_b+sonce+mraz+nmv | obs_b+sonce+mraz+nmv)
> nb <- zeroinfl(frm, dist="negbin", link="logit", data=zir2)
> Error in solve.default(as.matrix(fit$hessian)) :
>   system is computationally singular: reciprocal condition number =
> 3.87086e-25
> 
> Has anyone any idea how to solve this? It has been suggested that it's
> something in my data, but I don't know what to think if the cod parasite
> data shows different success/failures on different versions for the same
> model.

Try fitting a simpler model; you may simply not have enough information
in your data to fit such a complex model.

HTH

G

> Cheers,
> Roman
> 
> 

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