From jpnolan at american.edu  Wed May  7 16:11:05 2014
From: jpnolan at american.edu (John Nolan)
Date: Wed, 7 May 2014 10:11:05 -0400
Subject: [Rd] historical significance of Pr(>Chisq) < 2.2e-16
In-Reply-To: <536A3CE8.2010909@yorku.ca>
References: <536A3CE8.2010909@yorku.ca>
Message-ID: <OF66F27136.0095C443-ON85257CD1.004DEB75-85257CD1.004DEB76@american.edu>

Presumably from

> .Machine$double.eps
[1] 2.220446e-16

Whether this means the tail probability is actually that
small, or that the routine that computes it can't get
any more accuracy than that, you'll have to dig deeper.

John
 ..............................................................
 John P. Nolan
 Math/Stat Department
 227 Gray Hall,   American University
 4400 Massachusetts Avenue, NW
 Washington, DC 20016-8050

 jpnolan at american.edu       voice: 202.885.3140          
 web: academic2.american.edu/~jpnolan
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-----r-devel-bounces at r-project.org wrote: ----- 
To: r-devel <r-devel at r-project.org>
From: Michael Friendly 
Sent by: r-devel-bounces at r-project.org
Date: 05/07/2014 10:02AM
Subject: [Rd] historical significance of Pr(>Chisq) < 2.2e-16

Where does the value 2.2e-16 come from in p-values for chisq tests such 
as those
reported below?

 > Anova(cm.mod2)
Analysis of Deviance Table (Type II tests)

Response: Freq
LR Chisq Df Pr(>Chisq)
B 11026.2 1 < 2.2e-16 ***
W 7037.5 1 < 2.2e-16 ***
Age 886.6 8 < 2.2e-16 ***
B:W 3025.2 1 < 2.2e-16 ***
B:Age 1130.4 8 < 2.2e-16 ***
W:Age 332.9 8 < 2.2e-16 ***
---
Signif. codes: 0 ?***? 0.001 ?**? 0.01 ?*? 0.05 ?.? 0.1 ? ? 1
 >

-- 
Michael Friendly     Email: friendly AT yorku DOT ca
Professor, Psychology Dept. & Chair, Quantitative Methods
York University      Voice: 416 736-2100 x66249 Fax: 416 736-5814
4700 Keele Street    Web:   http://www.datavis.ca
Toronto, ONT  M3J 1P3 CANADA

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[Rd] historical significance of Pr(>Chisq) < 2.2e-16
John Nolan