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negative AIC and BIC values in gls
7 messages · Gary Dong, Jeremy Miles, David Winsemius +2 more
It's fine. Just interpret them as you would any other (lower is better).
On 22 August 2012 16:43, Gary Dong <pdxgary163 at gmail.com> wrote:
Dear R users,
I obtained negative AIC and BIC and positive Loglik values in a gls model.
Is this normal? how should I interpret them? Thanks!
AIC BIC logLik
-659.978 -587.5541 345.989
Best
Gary
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______________________________________________ R-help at r-project.org 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.
On Aug 22, 2012, at 5:17 PM, Jeremy Miles wrote:
It's fine. Just interpret them as you would any other (lower is better).
And it is the printed logLik that is out of step here. log-likelihoods _should_ be negative.
David. > > On 22 August 2012 16:43, Gary Dong <pdxgary163 at gmail.com> wrote: >> Dear R users, >> >> I obtained negative AIC and BIC and positive Loglik values in a gls >> model. >> Is this normal? how should I interpret them? Thanks! >> >> AIC BIC logLik >> -659.978 -587.5541 345.989 >> >> Best >> Gary David Winsemius, MD Alameda, CA, USA
Inline.
On Wed, Aug 22, 2012 at 5:17 PM, Jeremy Miles <jeremy.miles at gmail.com> wrote:
It's fine. Just interpret them as you would any other (lower is better).
I don't think so. I believe all 3 values are the negative of what they
should be. AIC is defined as -2*log(L) + k*{degrees of freedom for
model) . BIC is similar (different k's). This should be positive and,
as you said, the smaller the better. So if the signs are reversed,
models with lower absolute AIC and BIC -- bigger negative AIC and BIC
-- is what you want.
However, this really needs comment by an expert, which I ain't. I also
suggest you post to r-sig-mixed-models, since gls is an nlme function.
Cheers,
Bert
On 22 August 2012 16:43, Gary Dong <pdxgary163 at gmail.com> wrote:
Dear R users,
I obtained negative AIC and BIC and positive Loglik values in a gls model.
Is this normal? how should I interpret them? Thanks!
AIC BIC logLik
-659.978 -587.5541 345.989
Best
Gary
[[alternative HTML version deleted]]
______________________________________________ R-help at r-project.org 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.
______________________________________________ R-help at r-project.org 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.
Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
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O course! And for the same reason, my stupid comment should be ignored. -- Bert
On Thu, Aug 23, 2012 at 12:02 AM, Ingmar Visser <i.visser at uva.nl> wrote:
It's fine. Just interpret them as you would any other (lower is better).
And it is the printed logLik that is out of step here. log-likelihoods _should_ be negative.
That is not quite the case; in models with small variances log-likelihoods can easily become positive, consider eg:
dnorm(0,0,0.1,log=T)
[1] 1.383647 hth, Ingmar
-- David.
On 22 August 2012 16:43, Gary Dong <pdxgary163 at gmail.com> wrote:
Dear R users,
I obtained negative AIC and BIC and positive Loglik values in a gls
model.
Is this normal? how should I interpret them? Thanks!
AIC BIC logLik
-659.978 -587.5541 345.989
Best
Gary
David Winsemius, MD Alameda, CA, USA
______________________________**________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help> PLEASE do read the posting guide http://www.R-project.org/** posting-guide.html <http://www.R-project.org/posting-guide.html> and provide commented, minimal, self-contained, reproducible code.
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______________________________________________ R-help at r-project.org 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.
Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
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