[R] Using Anova Sums of Squares

[Maarten Speekenbrink]

Dear all,

I'm trying to access the Sums of Squares resulting from a summary(aov(....)) so I can use them in a function. Is there an easy way to access these? 

The structure of a summary.aov object is something like this:

> str(summary(fhc.aov))
List of 5
 $ Error: PPNR        :List of 1
  ..$ :Classes anova  and `data.frame': 1 obs. of  5 variables:
  .. ..$ Df     : num 70
  .. ..$ Sum Sq : num 70.7
  .. ..$ Mean Sq: num 1.01
  .. ..$ F value: num NA
  .. ..$ Pr(>F) : num NA
  ..- attr(*, "class")= chr [1:2] "summary.aov" "listof"
 $ Error: PPNR:CONSENS:List of 1
  ..$ :Classes anova  and `data.frame': 2 obs. of  5 variables:
  .. ..$ Df     : num [1:2] 1 70
  .. ..$ Sum Sq : num [1:2]  0.254 70.746
  .. ..$ Mean Sq: num [1:2] 0.254 1.011
  .. ..$ F value: num [1:2] 0.251    NA
  .. ..$ Pr(>F) : num [1:2] 0.618    NA
  ..- attr(*, "class")= chr [1:2] "summary.aov" "listof"
 
...etc.

but calling summary(fhc.aov)[2]$"Sum Sq" or anything like it (i.e. summary(fhc.aov)[2][2] or summary(fhc.aov)[2][1][2]) results in a Na. The only way I've been able to get it is by unlist(summary(fhc.aov)[2]), which does result in a list with the right number of elements, but this is not very handy for indexing... Of course I could recompute the Sums of Squares, but since summary(aov(...)) already gives them, I would rather get them from there. Thanks for your help,

Maarten Speekenbrink

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