[R] Difference between P.Value and adj.P.Value

[john seers (IFR)]

Hi Corinna

The p.adjusted value is the the p-value adjusted for Multiple
Comparisons.

Enter ?p.adjust to get more of an explanation.

Regards


JS

 
---
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Schmitt, Corinna
Sent: 11 February 2008 16:02
To: r-help at r-project.org
Subject: [R] Difference between P.Value and adj.P.Value

Hallo,


> fit12<-lmFit(qrg[,1:2])
> t12<-toptable(fit12,adjust="fdr",number=25,genelist=qrg$genes[,1])
> t12
            ID     logFC         t      P.Value  adj.P.Val        B
522    PLAU_OP -6.836144 -8.420414 5.589416e-05 0.01212520 2.054965
1555  CD44_WIZ -6.569622 -8.227938 6.510169e-05 0.01212520 1.944046

Can anyone tell me what the difference is between P.Value and
adj.P.Value? I need to analyse microarrays and should say if there exist
differential expressed genes. Which P.Value should I use?

Thanks, Corinna

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