[R] How to read ANOVA output

[Gavin Simpson]

On Wed, 2010-08-18 at 00:42 -0700, Stephen Liu wrote:
> Hi folks,
> 
> 
> Where can I find document re "how to read anova output"?  Google found many of 
> them.  But seemingly non of them can explain to me following output:-
> 
> 
> > tabA = c(5.67, 5.67, 5.55, 5.57)
> > tabB = c(5.75, 5.47, 5.43, 5.45)
> > tabC = c(4.74, 4.45, 4.65, 4.94)
> > tabs = data.frame(tabA, tabB, tabC)
> 
> > tablets = stack(tabs)
> 
> 
> > anova(lm(values ~ ind, data = tablets))
> Analysis of Variance Table
> Response: values
>       Df  Sum Sq   Mean Sq  F value  Pr(>F)
> ind      2   2.05787  1.02893  45.239   2.015e-05 ***
> Residuals 9   0.20470  0.02274
> ---
> Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

That output is designed to look like ANOVA tables from classical text
books, so any introductory textbook designed for your particular
background or area of knowledge would probably help you understand it.
Many of the R books that do introductory stats aren't really concerned
with teaching the stats side of things so might not go into much detail
explaining the table, assuming that this is covered elsewhere. There
will be exceptions of course.

HTH

G

> 
> > TukeyHSD(aov(values ~ ind, data = tablets))
> Tukey multiple comparisons of means
> 95% family-wise confidence level
> Fit: aov(formula = values ~ ind, data = tablets)
> $ind
>         diff  lwr           upr      p adj
> tabB-tabA  -0.09  -0.3877412   0.2077412  0.6866791
> tabC-tabA  -0.92  -1.2177412  -0.6222588  0.0000321
> tabC-tabB  -0.83  -1.1277412  -0.5322588  0.0000731
> 
> 
> Please help.  TIA
> 
> 
> B.R.
> Stephen L
> 
> 
> 
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