From martin.becker at mx.uni-saarland.de  Thu Feb  7 18:08:05 2008
From: martin.becker at mx.uni-saarland.de (Martin Becker)
Date: Thu, 07 Feb 2008 18:08:05 +0100
Subject: [Rd] pnorm
In-Reply-To: <BAY127-W15EFA85D9E6F501736E0CFA52E0@phx.gbl>
References: <BAY127-W15EFA85D9E6F501736E0CFA52E0@phx.gbl>
Message-ID: <47AB3AF5.3060605@mx.uni-saarland.de>

I guess that you destroy the accuracy of the calculation by the 
subtraction. Try
  2*(pnorm(8.104474,lower=FALSE))
instead, which results in
  5.29742e-16
for me.

Regards,
  Martin



jing hua zhao schrieb:
> Dear R list,
>
> I calculated a two-sided p values according to 2*(1-pnorm(8.104474)), which gives  4.440892e-16. However, it appears to be  5.30E-16 by a colleague and 5.2974E-16 from SAS. I tried to get around with mvtnorm package but it turns out to be using pnorm for univariate case. I should have missed some earlier discussions, but for the moment is there any short answer for a higher precision? Somehow these days, statistical geneticists are infatuated with such tiny p values!
>
> Many thanks in advance,
>
>
> Jing Hua
>
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[Rd] pnorm
Martin Becker