Yea the anova object seems to be odd. It's not S4 so that's why I tried originally the attr() funtion but....

summary(pb)$Pr(>F)

Error: unexpected '>' in "summary(pb)$Pr(>"
> summary(pb)$Pr

NULL
> summary(pb)@Pr(>F)

Error: unexpected '>' in "summary(pb)@Pr(>"
> summary(pb)@Pr(F)

Error: no slot of name "Pr" for this object of class "summary.aov"
In addition: Warning message:
trying to get slot "Pr" from an object (class "summary.aov") that is
not an S4 object
>

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Mass Spectrometry Core Facility
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markleeds@verizon.net wrote:
>  Hi: it's probably the Pr(> F) element so just access it by
>
> sum<-summary(whatever).
>
> then sum$Pr(>F) will probably work. But make sure that's it because 
> usually the name is pval or pvalue etc so I'm
> surprised about the weird name.
>
>
>
>
> On Wed, May 7, 2008 at  8:47 PM, Paul Benton wrote:
>
>> hello all,
>>
>> Quick question, how do I get the p value out of the anova?
>>
>> Thanks,
>>
>> Paul
>>
>>> pb<-aov(as.numeric(diff[5,16:33]) ~ grF)
>>> summary(pb)
>>             Df     Sum Sq    Mean Sq F value  Pr(>F)
>> grF          3 2.7860e+10 9.2867e+09  4.2236 0.02534 *
>> Residuals   14 3.0783e+10 2.1988e+09
>> ---
>> Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
>>> str(summary(pb))
>> List of 1
>>  $ :Classes 'anova' and 'data.frame':   2 obs. of  5 variables:
>>   ..$ Df     : num [1:2] 3 14
>>   ..$ Sum Sq : num [1:2] 2.79e+10 3.08e+10
>>   ..$ Mean Sq: num [1:2] 9.29e+09 2.20e+09
>>   ..$ F value: num [1:2] 4.22   NA
>>   ..$ Pr(>F) : num [1:2] 0.0253     NA
>>  - attr(*, "class")= chr [1:2] "summary.aov" "listof"
>>> attr(summary(pb), "Pr(>F)")
>> NULL
>>
>> ______________________________________________
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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.
>
>

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