Re: [R] unbalanced anova with subsampling (Type III SS)

From: John Fox <jfox_at_mcmaster.ca>
Date: Sat, 21 May 2011 09:46:48 -0400


Dear Sam,

I don't think that you can use the Anova() function in the car package for this design because there would be no way to specify the error term.

Sorry,
 John



John Fox
Senator William McMaster
  Professor of Social Statistics
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
http://socserv.mcmaster.ca/jfox

> -----Original Message-----
> From: r-help-bounces_at_r-project.org
> [mailto:r-help-bounces_at_r-project.org]
> On Behalf Of Sam Chand
> Sent: May-20-11 11:15 PM
> To: r-help_at_r-project.org
> Subject: [R] unbalanced anova with subsampling (Type III SS)
>
> Hello R-users,
> I am trying to obtain Type III SS for an ANOVA with subsampling. My
> design is slightly unbalanced with either 3 or 4 subsamples per
> replicate.
>
> The basic aov model would be:
> fit <- aov(y~x+Error(subsample))
>
> But this gives Type I SS and not Type III.
>
> But, using the drop() option:
> drop1(fit, test="F")
>
> I get an error message:
> "Error in UseMethod("extractAIC") : no applicable method for
> "extractAIC"
>
> Changing the "contrasts" to "contr.helmert", "contr.poly" also does
> not help.
>
> Can I use library(car) for unbalanced subsamples?
>
> I am very confused.
> Any help would be greatly appreciated.
> -Sam
>
> [[alternative HTML version deleted]]
>
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Sat 21 May 2011 - 13:50:54 GMT

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