# [R] Multiple ANOVA tests

Imri bisrael at agri.huji.ac.il
Wed May 27 14:23:30 CEST 2009

```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
> 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.

```