Re: [R] R2WinBugs and Compare DIC versus BIC or AIC

From: Dae-Jin Lee <dae-jin.lee_at_uc3m.es>
Date: Mon 15 Jan 2007 - 16:05:25 GMT

Thanks for your answer !

But If I have understood correctly, the procedure is correct and this only means that I have already generated the initial values

>From R. I define a function to generate the initial values as:

inits. <- function(){list(sdesp=runif(1),sdhet=runif(1),beta0=runif(1), beta1=runif(1), b=rnorm(n), phi=rnorm(n))}

then It is not necessary to generate initial values, that why gen.inits() is greyed out
, is it ok?

Here is what Winbugs show


display(log)
check(D:/model.txt)
model is syntactically correct
data(D://data.txt)
data loaded
compile(3)
model compiled
inits(1,D:/inits1.txt)
chain initialized but other chain(s) contain uninitialized variables inits(2,D:/inits2.txt)
chain initialized but other chain(s) contain uninitialized variables inits(3,D:/inits3.txt)
model is initialized
gen.inits()

command #Bugs:gen.inits cannot be executed (is greyed out) thin.updater(1)
update(5000)


Thank again in advance

Dae-Jin

2007/1/13, Uwe Ligges <ligges@statistik.uni-dortmund.de >:
>
>
>
> Dae-Jin Lee wrote:
> > Dear All
> >
> > 1)
> >
> > I'm fitting spatial CAR models
> >
> > using R2Winbugs and although everything seems to go reasonably well (or
> I
> > think so)
> >
> > the next message appears from WINBUGS 1.4 window:
> >
> > gen.inits()
> > Command #Bugs: gen.inits cannot be executed (is greyed out)
>
> "greyed out" refers to the corresponding GUI. In this case it could mean
> that either your preparations before were not successful or you have
> already specified all initial values and no further have to be
> generated. But this is a WinBUGS question and not R related.
>
> Perhaps you have transposed some matrix? This is always extremely
> confusing ...
>
>
> > The question is if this message means that something is wrong and the
> > results are consequently wrong, or Can I assume it as a simple warning
> > message???...
> >
> > I've tried to fit the model using just WinBugs (not calling form R) and
> > gen.inits command is available and the results obtain are practically
> the
> > same...
> >
> > 2)
> >
> > The other question is, once several bayesian CAR models are fitted I use
> DIC
> > to model selection
> >
> > How can I compare DIC with AIC or BIC obtain for a spatial glm? I mean
> for
> > example:
> >
> > - DIC of 300 and Pd of 32
> >
> > versus
> >
> > - BIC of 220 and Effective dimension (measured of trace of hat matrix)
> equal
> > to 14
> >
> > * I've read that DIC is intended as a generalisation of Akaike's
> Information
> > Criterion (AIC), but is it possible to compare them simply looking which
> is
> > the lowest???
>
>
> Well they are intended to be compared (DIC with DIC, AIC with AIC, but
> do not mix them!) that way given you are comparing within the same class
> of models. And then, there is a bit of fortunetelling with all these
> information criterion, at least in my personal opinion (and I know that
> others disagree).
>
> Uwe Ligges
>
>
> >
> > Thanks,
> >
> > Dae-Jin Lee
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>

        [[alternative HTML version deleted]]



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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Tue Jan 16 03:17:24 2007

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