[R] Indexing in anova summary output of the form: summary(aov(y ~ x1, Error = (x1/x2)))

[Michael D. Rennie]

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