Doubt about nested aov output
That's great. In your example, the aov fit is following by a warning:
> res2 <- aov(y ~ fix + Error(fix/R1/R2), data = dat)
Warning message:
Error() model is singular in: aov(y ~ fix + Error(fix/R1/R2), data = dat)
Moreover, to test whether your change was statistically significant,
library(nlme) supports "anova" with two nested models. In this case, it
produced the following:
> anova(reslme, reslme2)
Model df AIC BIC logLik Test L.Ratio p-value
reslme 1 6 864.4973 881.0704 -426.2487
reslme2 2 7 866.4973 885.8325 -426.2487 1 vs 2 1.818989e-12 1
>
I don't know if this relates to Ronaldo Reis' question, but it
certainly seems plausible.
spencer graves
Christoph Buser wrote:
Hi
I think the problem is related to specifying "Tratamento" both
as a fixed factor and in the error term. I attached a script
with a reproducible example that shows a similar output.
I do not know the details of the original data and the questions
of interest, but maybe a model including "Tratamento" is more
what you wanted to implement.
Regards,
Christoph
## R-Script
library(nlme)
## Generating the data
set.seed(1)
ziel <- rep(c(-6,8,20), each = 40) + rep(rnorm(15, 0, 20), each = 4) +
rep(rnorm(60, 0, 10), each = 2) + rnorm(120, 0, 3)
dat <- data.frame(y = ziel,
fix = factor(rep(1:3, each = 40)),
R1 = factor(rep(1:15, each = 8)),
R2 = factor(rep(1:60, each = 2)))
## Model including "fix" as fixed and random effect.
res2 <- aov(y ~ fix + Error(fix/R1/R2), data = dat)
summary(res2)
reslme2 <- lme(y ~ fix , data = dat, random = ~ 1|fix/R1/R2)
summary(reslme2)
anova(reslme2)
## Model including "fix" as fixed factor.
res1 <- aov(y ~ fix + Error(R1/R2), data = dat)
summary(res1)
reslme <- lme(y ~ fix , data = dat, random = ~ 1|R1/R2)
summary(reslme)
anova(reslme)
--------------------------------------------------------------
Christoph Buser <buser at stat.math.ethz.ch>
Seminar fuer Statistik, LEO C13
ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND
phone: x-41-44-632-4673 fax: 632-1228
http://stat.ethz.ch/~buser/
--------------------------------------------------------------
Spencer Graves writes:
> Others may know the answer to your question, but I don't. However, > since I have not seen a reply, I will offer a few comments: > > 1. What version of R are you using? I just tried superficially > similar things with the examples in ?aov in R 2.1.1 patched and > consistently got F and p values. > > 2. My preference for this kind of thing is to use lme in > library(nlme) or lmer in library(lme4). Also, I highly recommend > Pinheiro and Bates (2000) Mixed-Effects Models in S and S-Plus (Springer). > > 3. If still want to use aov and are getting this problem in R 2.1.1, > could you please provide this list with a small, self contained example > that displays the symptoms that concern you? And PLEASE do read the > posting guide! "http://www.R-project.org/posting-guide.html". It might > increase the speed and utility of replies. > > spencer graves > > Ronaldo Reis-Jr. wrote: >
> > Hi, > > > > I have two doubts about the nested aov output. > > > > 1) I have this: > >
> >>anova.ratos <- aov(Glicogenio~Tratamento+Error(Tratamento/Rato/Figado)) > >>summary(anova.ratos)
> > > > > > Error: Tratamento > > Df Sum Sq Mean Sq > > Tratamento 2 1557.56 778.78 > > > > Error: Tratamento:Rato > > Df Sum Sq Mean Sq F value Pr(>F) > > Residuals 3 797.67 265.89 > > > > Error: Tratamento:Rato:Figado > > Df Sum Sq Mean Sq F value Pr(>F) > > Residuals 12 594.0 49.5 > > > > Error: Within > > Df Sum Sq Mean Sq F value Pr(>F) > > Residuals 18 381.00 21.17 > > > > R dont make the F and P automatically, it is possible? > > > > I Like an output like this: > > > > Error: Tratamento > > Df Sum Sq Mean Sq F value Pr(>F) > > Tratamento 2 1557.56 778.78 2.929 0.197 > > > > Error: Tratamento:Rato > > Df Sum Sq Mean Sq F value Pr(>F) > > Residuals 3 797.67 265.89 5.372 0.0141 > > > > Error: Tratamento:Rato:Figado > > Df Sum Sq Mean Sq F value Pr(>F) > > Residuals 12 594.0 49.5 2.339 0.0503 > > > > Error: Within > > Df Sum Sq Mean Sq F value Pr(>F) > > Residuals 18 381.00 21.17 > > > > Why it not make automatic calculations? It is possible? > > > > > > 2) I can say that Error: Tratamento:Rato means an interaction between > > Tratamento and Rato? Normally the : represents an interaction, but in this > > output I think that it dont mean the interaction. > > > > Any explanation are welcome. > > > > Thanks > > Ronaldo
> > -- > Spencer Graves, PhD > Senior Development Engineer > PDF Solutions, Inc. > 333 West San Carlos Street Suite 700 > San Jose, CA 95110, USA > > spencer.graves at pdf.com > www.pdf.com <http://www.pdf.com> > Tel: 408-938-4420 > Fax: 408-280-7915 > > ______________________________________________ > R-help at 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 > > > !DSPAM:431b8510220677348368323!
Spencer Graves, PhD Senior Development Engineer PDF Solutions, Inc. 333 West San Carlos Street Suite 700 San Jose, CA 95110, USA spencer.graves at pdf.com www.pdf.com <http://www.pdf.com> Tel: 408-938-4420 Fax: 408-280-7915