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

From: Michael D. Rennie <mrennie_at_utm.utoronto.ca>
Date: Thu 05 Apr 2007 - 18:03:04 GMT

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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