[R-lang] Re: aov in R

[T. Florian Jaeger]

This post by Klinton Bicknell might also be useful:

http://hlplab.wordpress.com/2014/03/17/old-and-new-lme4/

On Fri, Apr 4, 2014 at 4:03 PM, João Veríssimo <jl.verissimo@gmail.com>wrote:

> Hi Zhenguang,
>
> Your aov() command seems right to me.
> I haven't tried this in SPSS, but in R, I get the same F-value (37.08),
> either using t.test(), aov(), or ezANOVA(); see code below.
>
> Maybe check your SPSS analysis to see what's going on there?
>
> Best,
> João
>
> ## Import data
> MT2F1 <- read.table("./MT2-F1.txt", header=T)
> str(MT2F1)
> ## Convert Subject to factor
> MT2F1$Subject <- as.factor(MT2F1$Subject)
>
> ## Paired t-test
> (myttest <- t.test(MT2F1$Average~MT2F1$Perspective, paired=T))
> myttest$statistic[[1]]^2
>
> ## Repeated-measures ANOVA (with aov())
> summary(aov(Average~Perspective+Error(Subject/Perspective), MT2F1))
>
> ## Repeated-measures ANOVA (with ezANOVA())
> library(ez)
> ezANOVA(
>   data = MT2F1
>   , dv = Average
>   , wid = Subject
>   , within = Perspective
> )
>
> On Fri, 2014-04-04 at 17:50 +0100, Zhenguang Cai wrote:
> > Hi,
> >
> > I keep having radically different results for LME (especially when
> > random slopes are included, due to Barr et al. 2013) between different
> > versions of R (and supposedly different lme4 packages)  (I wonder
> > anyone else encounter similar problems), so I am turning back to the
> > good old ANOVA.
> >
> > I had a repeated measure design, with Perspective as  two-level
> > within-subject factor (Agent vs. Recipient). So I ran an ANOVA
> > analysis in R, using
> >
> > aov(Average~Perspective+Error(Subject/Perspective), MT2F1)
> >
> > and the following are the results
> >
> > ***********************
> > Error: Subject
> >           Df Sum Sq Mean Sq F value Pr(>F)
> > Residuals 22  3.176  0.1444
> >
> > Error: Subject:Perspective
> >             Df Sum Sq Mean Sq F value   Pr(>F)
> > Perspective  1 1.1414  1.1414   37.08 3.96e-06 ***
> > Residuals   22 0.6772  0.0308
> > ---
> > Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
> > *************************
> >
> > However, I found the F-value was much larger than the F-value (37.08)
> > I observed in SPSS (5.92) (using the same data set). I wonder whether
> > I used a wrong formula.
> >
> > Also, I want to include a covariate "Pnum". I wonder the following is
> > the correct formula:
> >
> > aov(Average~(Perspective+Pnum)+Error(Subject/Perspective), MT2F1)
> >
> > Thanks,
> >
> > Zhenguang Cai
> >
> > --
> > Zhenguang Cai
> >
> > Department of Cogntive, Perceptual and Brain Sciences
> > University College London
> >
> > https://sites.google.com/site/zhenguangcai/
>
>
>
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