Message-ID: <23277778.post@talk.nabble.com>
Date: 2009-04-28T14:04:31Z
From: Ben Bolker
Subject: Why there is no p-value from likelihood ratio test using anova in GAM model fitting?
In-Reply-To: <23277535.post@talk.nabble.com>
willow1980 wrote:
>
> Hi, Dieter,
> I did add (test="F") in my script, but it does not matter. The following
> is my whole script.
>
> #################################################################
> modelsurs_fer13<-gam(sum_surv15~s(FLBS)+SES+s(byear)+s(FLBS,byear),family=quasipoisson)
> modelsurs_fer14<-gam(sum_surv15~s(FLBS)+s(byear)+s(FLBS,byear),family=quasipoisson)
> anova.gam(modelsurs_fer14,modelsurs_fer13,test="F")
> #################################################################
>
> Would you please make further suggestions? Thank you in advance!
> Jianghua
>
>
We can't make further suggestions until you (1) provide the output of
sessionInfo() ;
(2) provide a reproducible example.
The following example works for me:
library(mgcv)
example(anova.gam)
b1 <- gam(y~x0+s(x1)+s(x2),family=quasipoisson,data=dat)
b2 <- gam(y~x0+s(x1),family=quasipoisson,data=dat)
anova.gam(b1,b2,test="F")
Analysis of Deviance Table
Model 1: y ~ x0 + s(x1) + s(x2)
Model 2: y ~ x0 + s(x1)
Resid. Df Resid. Dev Df Deviance F Pr(>F)
1 187.9672 83.684
2 194.2014 226.042 -6.2342 -142.358 51.291 < 2.2e-16 ***
Unless you can provide us with an example that _will not work_
when we run it, it will be hard for us to help you.
Ben Bolker
--
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