From landronimirc at gmail.com  Sun Aug 16 12:38:40 2009
From: landronimirc at gmail.com (Liviu Andronic)
Date: Sun, 16 Aug 2009 11:38:40 +0100
Subject: [Rd] Printing the null hypothesis
Message-ID: <68b1e2610908160338k3b5634acu675c26144d2bb43e@mail.gmail.com>

Dear R developers,
Currently many (all?) test functions in R describe the alternative
hypothesis, but not the the null hypothesis being tested. For example,
cor.test:
> require(boot)
> data(mtcars)
> with(mtcars, cor.test(mpg, wt, met="kendall"))

	Kendall's rank correlation tau

data:  mpg and wt
z = -5.7981, p-value = 0.000000006706
alternative hypothesis: true tau is not equal to 0
sample estimates:
     tau
-0.72783

Warning message:
In cor.test.default(mpg, wt, met = "kendall") :
  Cannot compute exact p-value with ties


In this example,
H0: (not printed)
Ha: true tau is not equal to 0

This should be fine for the advanced users and expert statisticians,
but not for beginners. The help page will also often not explicitely
state the null hypothesis. Personally, I often find myself in front of
an htest object guessing what the null should have reasonably sounded
like.

Are there compelling reasons for not printing out the null being
tested, along with the rest of the results? Thank you
Liviu





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[Rd] Printing the null hypothesis
Liviu Andronic