R help - Sep 2008 - ANOVA between & within variance

hi,
is there an option to calculate the 'within' & 'between'
group variances
for a simple ANOVA (aov) model (2 groups, 1 trait, normally distr.) ?
or do I have to calculate them from the Sum Sq ?

thanks for your time and greetings,

gregor


-- 
Gregor Rolshausen
	
PhD Student; University of Freiburg, Germany

e-mail: gregor.rolshausen at biologie.uni-freiburg.de	
tel.  : ++49 761 2032559

dear Dr. Kubovy,

I am sorry. but the Variance table is not exactly what I want. I want  
the partitioned VARIANCE for between and within the groups. the anova 
()-table just gives me the SumSq and the mean Sq... I know how to run  
t.test and ANOVA!
in the nlme-package there is the VarCorr function, which extracts the  
between and within variances, but only for nested ANOVAs. so my  
question was, if there is a function like that for not-nested ANOVAS ?

sorry. maybe I should reformulate the question.

cheers ,
gregor






Am Sep 27, 2008 um 7:19 AM schrieb Michael Kubovy:
> Than all you need is to run a t-test, no?  More generally (from ?lm):
>
> ctl <- c(4.17,5.58,5.18,6.11,4.50,4.61,5.17,4.53,5.33,5.14)
> trt <- c(4.81,4.17,4.41,3.59,5.87,3.83,6.03,4.89,4.32,4.69)
> group <- gl(2,10,20, labels=c("Ctl","Trt"))
> weight <- c(ctl, trt)
> anova(lm.D9 <- lm(weight ~ group))
> This gives you what you need:
> Analysis of Variance Table
>
> Response: weight
>           Df Sum Sq Mean Sq F value Pr(>F)
> group      1   0.69    0.69    1.42   0.25
> Residuals 18   8.73    0.48
> I am concerned that you have not spent enough time either studying  
> stats or reading up on R. There are many good introductions to  
> stats using R.
> _____________________________
> Professor Michael Kubovy
> University of Virginia
> Department of Psychology
> USPS:     P.O.Box 400400    Charlottesville, VA 22904-4400
> Parcels:    Room 102        Gilmer Hall
>         McCormick Road    Charlottesville, VA 22903
> Office:    B011    +1-434-982-4729
> Lab:        B019    +1-434-982-4751
> Fax:        +1-434-982-4766
> WWW:    http://www.people.virginia.edu/~mk9y/
>
Gregor Rolshausen
PhD Student
Department of Evolutionary Ecology
University of Freiburg im Breisgau; Hauptstrasse 1, 79108 Freiburg
phone - +49.761.2559
email - gregor.rolshausen@biologie.uni-freiburg.de




	[[alternative HTML version deleted]]

So, rather than the estimated between and within group variances from
a standard fixed-effects ANOVA (i.e. the Mean Sqs in the anova table),
you are looking for the estimated variance components from a model
with crossed random effects?  If so, you may find the lmer function
found in package lme4 to be useful (formulas for crossed random
effects are much more straightforward than in nlme).  If not, this
page provides some helpful tips on eliciting useful responses from
this list: http://www.r-project.org/posting-guide.html

HTH,

Kingsford Jones

On Sat, Sep 27, 2008 at 2:21 AM, Gregor Rolshausen
<gregor.rolshausen at biologie.uni-freiburg.de>
wrote:
> dear Dr. Kubovy,
>
> I am sorry. but the Variance table is not exactly what I want. I want
> the partitioned VARIANCE for between and within the groups. the anova
> ()-table just gives me the SumSq and the mean Sq... I know how to run
> t.test and ANOVA!
> in the nlme-package there is the VarCorr function, which extracts the
> between and within variances, but only for nested ANOVAs. so my
> question was, if there is a function like that for not-nested ANOVAS ?
>
> sorry. maybe I should reformulate the question.
>
> cheers ,
> gregor
>
>
>
>
>
>
> Am Sep 27, 2008 um 7:19 AM schrieb Michael Kubovy:
>
>> Than all you need is to run a t-test, no?  More generally (from ?lm):
>>
>> ctl <- c(4.17,5.58,5.18,6.11,4.50,4.61,5.17,4.53,5.33,5.14)
>> trt <- c(4.81,4.17,4.41,3.59,5.87,3.83,6.03,4.89,4.32,4.69)
>> group <- gl(2,10,20, labels=c("Ctl","Trt"))
>> weight <- c(ctl, trt)
>> anova(lm.D9 <- lm(weight ~ group))
>> This gives you what you need:
>> Analysis of Variance Table
>>
>> Response: weight
>>           Df Sum Sq Mean Sq F value Pr(>F)
>> group      1   0.69    0.69    1.42   0.25
>> Residuals 18   8.73    0.48
>> I am concerned that you have not spent enough time either studying
>> stats or reading up on R. There are many good introductions to
>> stats using R.
>> _____________________________
>> Professor Michael Kubovy
>> University of Virginia
>> Department of Psychology
>> USPS:     P.O.Box 400400    Charlottesville, VA 22904-4400
>> Parcels:    Room 102        Gilmer Hall
>>         McCormick Road    Charlottesville, VA 22903
>> Office:    B011    +1-434-982-4729
>> Lab:        B019    +1-434-982-4751
>> Fax:        +1-434-982-4766
>> WWW:    http://www.people.virginia.edu/~mk9y/
>>
>
> Gregor Rolshausen
> PhD Student
> Department of Evolutionary Ecology
> University of Freiburg im Breisgau; Hauptstrasse 1, 79108 Freiburg
> phone - +49.761.2559
> email - gregor.rolshausen at biologie.uni-freiburg.de
>
>
>
>
>        [[alternative HTML version deleted]]
>
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