Hi, there
Sorry- I excluded some example code in the haste of my original e-mail.
Please find it included below. Note, however, that the elements in the
list in the summary output appear to be the anova tables themselves-
what I need to do is get inside the anova tables (execute the code below
to see what I mean...)
Thanks again,
Mike
#example code to illustrate my inability to get at a mean square in
anova output from
# models of the form summary(aov(y ~ x1 + Error(x1/x2)))
y<-rnorm(30,10)
x1<-rep(1:2, each=15)
x2<-rep(1:3, each=1, times=10)
dat<-data.frame(y, x1, x2)
dat
ex.aov<-aov(y ~ x1 + Error(x1/x2))
ex.sum<-summary(ex.aov)
ex.sum
#gets you the first list in the element, which is anova output for x1
caluclated with nested factor x2 in x1
ex.sum[1]
ex.sum[1]$Error #this is equivalent to...
ex.sum[[1]]
# since ex.sum is a list composed of anova tables, apparently the
element in the list
#is the anova table itself. The question is, how do you get at the
elements in each table
#(i.e., Mean Square?)
Prof Brian Ripley wrote:
The output is of class "summary.anovalist" so (hint, hint) it is a list.
Try [[ ]] to get list elements.
Without a reproducible example (see the footer and the posting guide)
it is not possible to show you working code.
On Thu, 5 Apr 2007, Michael D. Rennie wrote:
Hi, there
I'm trying to get the value of the Mean Square from the ANOVA model
summary that comes from specifying the error term, and am wondering
if one can actually do this ( I know it's possible when using
anova(lm) objects and the like, but I'm having a tough time with it
under this framework). There does appear to be some indexing in the
output of this type, but perhaps not enough to obtain single values?
Here's what I've been able to do so far with some example code:
density.aov<-aov(density ~ substrate + Error(substrate/tile))
anov1<-(summary(density.aov))
print(anov1)
Error: substrate
Df Sum Sq Mean Sq
substrate 2 1282.4 641.2
Error: substrate:tile
Df Sum Sq Mean Sq F value Pr(>F)
Residuals 27 225.700 8.359 Error: Within
Df Sum Sq Mean Sq F value Pr(>F)
Residuals 60 640.00 10.67
anov1[1]
$`Error: substrate`
Df Sum Sq Mean Sq
substrate 2 1282.4 641.2
anov1[2]
$`Error: substrate:tile`
Df Sum Sq Mean Sq F value Pr(>F)
Residuals 27 225.700 8.359 And, I can get
anov1[1]$Error
Df Sum Sq Mean Sq
substrate 2 1282.4 641.2
a<-anov1[1]$Error
and then tried to get at elements in that, trying things like
a$Mean
or
a[,2]
but all return
Error: incorrect number of dimensions
probably because
length(a)
[1] 1
Does anyone have any reccomendations on how to go any further here?
Cheers,
Mike
--
Michael D. Rennie
Ph.D. Candidate
University of Toronto at Mississauga
3359 Missisagua Rd. N.
Mississauga, ON L5L 1C6
Ph: 905-828-5452 Fax: 905-828-3792
www.utm.utoronto.ca/~w3rennie
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