[R] Multiple ANOVA tests

[Mike Lawrence]

you could use ldply from the plyr package:

p = ldply(q,function(x){x$P})

Without you data I can't confirm that works, but something like that
should do it

On Wed, May 27, 2009 at 9:23 AM, Imri <bisrael at agri.huji.ac.il> wrote:
>
> Thanks for the answer!!!
> I Know how to extract the Pr(>F) value from single ANOVA table, but I have a
> list of many ANOVA tables recived by :
> a<-function(x)(aov(MPH~x))
> q<-apply(assoc[,18:20],2,a) # just for example, I have more than 3
> factors(x)
>
>> print(q)
> $X11_20502
>             Df  Sum Sq Mean Sq F value    Pr(>F)
> x             3   369.9   123.3   6.475 0.0002547 ***
> Residuals   635 12093.2    19.0
> ---
> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
> 246 observations deleted due to missingness
>
> $X11_21067
>             Df  Sum Sq Mean Sq F value Pr(>F)
> x             1    26.7    26.7  1.3662 0.2429
> Residuals   637 12436.4    19.5
> 246 observations deleted due to missingness
>
> $X11_10419
>             Df  Sum Sq Mean Sq F value    Pr(>F)
> x             3   527.8   175.9   9.361 4.621e-06 ***
> Residuals   635 11935.3    18.8
> ---
> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
> 246 observations deleted due to missingness
>
>> summary(q)
>          Length Class       Mode
> X11_20502 1      summary.aov list
> X11_21067 1      summary.aov list
> X11_10419 1      summary.aov list
>  How can I extract all the Pr(>F) values from q (not one by one)?
>
> Thanks
> Imri
>
>
>
> Mike Lawrence wrote:
>>
>> #create some data
>> y=rnorm(20)
>> x=factor(rep(c('A','B'),each=10))
>>
>> #run the anova
>> my_aov = aov(y~x)
>>
>> #summarize the anova
>> my_aov_summary = summary(my_aov)
>>
>> #show the anova summary
>> print(my_aov_summary)
>>
>> #lets see what's in the summary object
>> str(my_aov_summary)
>>
>> #looks like it's a list with 1 element which
>> #in turn is a data frame with columns.
>> #The "Pr(>F)" column looks like what we want
>> my_aov_summary[[1]]$P
>>
>> #yup, that's it. Grab the first value
>> p = my_aov_summary[[1]]$P[1]
>>
>>
>> On Wed, May 27, 2009 at 7:11 AM, Imri <bisrael at agri.huji.ac.il> wrote:
>>>
>>> Hi all -
>>> I'm trying to do multiple one-way ANOVA tests of different factors on the
>>> same variable. As a result I have a list with all the ANOVA tables, for
>>> exemple:
>>>
>>> $X11_20502
>>> Analysis of Variance Table
>>>
>>> Response: MPH
>>>           Df  Sum Sq Mean Sq F value    Pr(>F)
>>> x           3   369.9   123.3   6.475 0.0002547 ***
>>> Residuals 635 12093.2    19.0
>>> ---
>>> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
>>>
>>> $X11_21067
>>> Analysis of Variance Table
>>>
>>> Response: MPH
>>>           Df  Sum Sq Mean Sq F value Pr(>F)
>>> x           1    26.7    26.7  1.3662 0.2429
>>> Residuals 637 12436.4    19.5
>>>
>>> $X11_10419
>>> Analysis of Variance Table
>>>
>>> Response: MPH
>>>           Df  Sum Sq Mean Sq F value    Pr(>F)
>>> x           3   527.8   175.9   9.361 4.621e-06 ***
>>> Residuals 635 11935.3    18.8
>>> ---
>>> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
>>>
>>> My question is how can I extract from this list, just the Pr(>F) values
>>> for
>>> each x ?
>>> --
>>> View this message in context:
>>> http://www.nabble.com/Multiple-ANOVA-tests-tp23739615p23739615.html
>>> Sent from the R help mailing list archive at Nabble.com.
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> 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.
>>>
>>
>>
>>
>> --
>> Mike Lawrence
>> Graduate Student
>> Department of Psychology
>> Dalhousie University
>>
>> Looking to arrange a meeting? Check my public calendar:
>> http://tr.im/mikes_public_calendar
>>
>> ~ Certainty is folly... I think. ~
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> 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.
>>
>>
>
> --
> View this message in context: http://www.nabble.com/Multiple-ANOVA-tests-tp23739615p23741437.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.
>



-- 
Mike Lawrence
Graduate Student
Department of Psychology
Dalhousie University

Looking to arrange a meeting? Check my public calendar:
http://tr.im/mikes_public_calendar

~ Certainty is folly... I think. ~