[R] p-values < 2.2e-16 not reported

Bert Gunter gunter.berton at gene.com
Wed May 19 17:16:07 CEST 2010

If you believe P-values that small have any meaning at all, I have a bridge
to sell you... 

Bert Gunter
Genentech Nonclinical Statistics

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of Will Eagle
Sent: Wednesday, May 19, 2010 1:53 AM
To: r-help at r-project.org
Subject: [R] p-values < 2.2e-16 not reported

Dear all,

how can I get the exact p-value of a statistical test like cor.test() if 
the p-value is below the default machine epsilon value of 
.Machine$double.eps =  2.220446e-16?

At the moment smaller p-values are reported as "p-value < 2.2e-16".
.Machine$double.eps <- 1E-100 does not solve this issue, although this 
value should be used by the format.pval() function.

To know the exact p-values down to 1E-200 is very important since I have 
multiple tests which require a alpha error-threshold below 2.2E-16.

Thanks in advance,


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