From tucker at mpi.com  Mon Sep 13 20:57:42 2004
From: tucker at mpi.com (tucker@mpi.com)
Date: Mon Sep 13 20:57:44 2004
Subject: [Rd] propogation of rounding error for t.tests with unequal sample
	sizes (PR#7225)
Message-ID: <20040913185742.A1F341138D@slim.kubism.ku.dk>


# users would benefit from a warning about the behavior in the
# groups.unbalanced case below.  A propogation of difference is the variance
# calculation is leading to an apparently significant difference in
# means, even though the numeric values are all identical.  Obviously upon
# inspection the difference in means is meaningless, but users might be warned
# if all of the input data is identical

xx <- rep(2.10,80)

groups.balanced <- as.factor(c(rep("one",40),rep("two",40)))
groups.unbalanced <- as.factor(c(rep("one",44),rep("two",36)))

t.test(xx ~ groups.balanced)

t.test(xx ~ groups.unbalanced)



<<insert bug report here>>



--please do not edit the information below--

Version:
 platform = sparc-sun-solaris2.8
 arch = sparc
 os = solaris2.8
 system = sparc, solaris2.8
 status = 
 major = 1
 minor = 9.0
 year = 2004
 month = 04
 day = 12
 language = R

Search Path:
 .GlobalEnv, package:methods, package:stats, package:graphics, package:utils, Autoloads, package:base



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[Rd] propogation of rounding error for t.tests with unequal sample sizes (PR#7225)
tucker@mpi.com