[R] Pulling p values

[Peter Ehlers]

On 2011-02-26 04:12, Gallavan, Robert wrote:
> Hi folks,
>
> I'm doing ANOVA with multiple comparisons.  I've used both the TukeyHSD  function and the multcomp procedure.  In both cases, I get some tantalizing results such as this...
>
> e = aov(lm(d.all[,(n+4)] ~ d.all[,4])
>
> TukeyHSD(e)
>
>    Tukey multiple comparisons of means
>      95% family-wise confidence level
>
> Fit: aov(formula = lm(d.all[, (n + 4)] ~ d.all[, 4], contrast = C))
>
> $`d.all[, 4]`
>                                   diff               lwr               upr                p adj
> 10 mpk-0 mpk                                -0.677375 -1.1779417 -0.1768083   0.0071092
> 30 mpk-0 mpk                               -1.074500 -1.5750667 -0.5739333    0.0000656
> 30 mpk-10 mpk                             -0.397125 -0.8976917  0.1034417    0.1369760
>
> I ask for the pvalues and get...
>
> i = h$pvalues
> i
>     10 mpk - 0 mpk              30 mpk - 0 mpk                 30 mpk - 10 mpk
>     2.630022e-03                   2.288575e-05                       5.863517e-02
>
> It looks like a matrix, but it is a vector of length 3 and the third element, for example, is....
>
>> length(i)
> [1] 3
>> q = i[3]
>> q
> 30 mpk - 10 mpk
>       0.05863517
>
> The contrast label is bound to the p-value as a single element.

Well, 'bound to' just means that you have a vector with names.
So you can just unname() it.

But do let us in on your secret: what's 'h'?

>
> Does anyone know how to extract just the p-value from this procedure?  Or a simple way to generate these comparisons?
>
> Thanks,
>
> Bob Gallavan
> An obvious newbie

Newbies need to peruse the posting guide;
In particular, note the comment about HTML mail.

Peter Ehlers

>
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