From maechler at stat.math.ethz.ch  Fri Sep 24 17:09:16 2004
From: maechler at stat.math.ethz.ch (maechler@stat.math.ethz.ch)
Date: Fri Sep 24 17:09:22 2004
Subject: [Rd] bug in  power.t.test( ) (PR#7245)
Message-ID: <20040924150916.4CB0A10FD1@slim.kubism.ku.dk>

>>>>> "UweL" == Uwe Ligges <ligges@statistik.uni-dortmund.de>
>>>>>     on Fri, 24 Sep 2004 08:43:56 +0200 (CEST) writes:

    UweL> mai@ms.uky.edu wrote:
    >> Full_Name: Mai Zhou Version: 1.9.1 OS: Win XP
    >> Professional Submission from: (NULL) (12.222.227.93)
    >> 
    >> 
    >> 
    >>> power.t.test(n=25, delta=0.1, sig.level=1.1,
    >>> strict=TRUE, type="one.sample")
    >> 
    >> 
    >> One-sample t test power calculation
    >> 
    >> n = 25 delta = 0.1 sd = 1 sig.level = 1.1 power =
    >> 1.088311 alternative = two.sided
    >> 
    >> ### power can never be over one!  Of course, sig.level
    >> should not take value > 1 ### either.  ### Possible
    >> solution: A check in the input to truncate sig.level into
    >> [0, 1]??

    UweL> Well, an error (or at least warning) message seems to
    UweL> be more appropriate rather than silently changing some
    UweL> values, e.g. somehwere at the top of the functions
    UweL> body:

    UweL>      if(any(sig.level < 0 | sig.level > 1))
    UweL>               stop("sig.level must be in [0,1]")

yes, in principle;
thank you, Uwe!

Since  sig.level can also be NULL (which works with the way you
constructed the test - on purpose?), I'd use the test a bit
differently.

BTW, did you know that e.g., sig.level or delta can be *vectors*
giving vectorized results - at least in some cases...
That will hopefully leed to more documentation / code updates, 
but not for 2.0.0 I presume.

Martin Maechler


[Rd] bug in power.t.test( ) (PR#7245)
maechler@stat.math.ethz.ch