Re: [Rd] bug in power.t.test( ) (PR#7245)

From: <maechler_at_stat.math.ethz.ch>
Date: Sat 25 Sep 2004 - 01:09:16 EST


>>>>> "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



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https://stat.ethz.ch/mailman/listinfo/r-devel Received on Sat Sep 25 01:19:43 2004

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