Apart from making the observation that there are many applications of
tests that do not involve ethical considerations, I am not at all clear
how this example relates to one or two tailed testing.
There is certainly an argument that when trialling a new treatment (I
initially used the word 'testing' here, but figure that it may be
confused with the statistical test of the resultant data) it is
presumably expected to work. Consequently, if a person in the trial is
given a placebo, there is a clear expectation that he or she is being
disadvantaged - given an inferior treatment.
On the other hand, if a placebo is not used, the results of the trial
will be unclear. This will presumably disadvantage Society. The ethical
choice is then between disadvantaging a number of individuals by giving
them a treatment which is expected to be inadequate (rather than a
treatment which is expected to be better - but may not be!) and
disadvantaging society by reducing the increase in knowledge - which is
expected to advantage many people in the future.
This is certainly an ethical question (though I might argue that neither
choice is unethical if the choice is made ethically!) But I don't see
how the type of statistical test done in analysing the resultant data
can be ethical or not.
Regards,
Alan
Jerry Dallal wrote:
>
> Will Hopkins wrote:
> >
> > Jerry Dallal wrote, ironically:
> > >If you're doing a 1 tailed test, why test at all? Just switch from
> > >standard treatment to the new one. Can't do any harm. Every field
> > >is littered with examples where one-tailed tests would have led to
> > >disasters (harmful treatments missed, etc.) had they been used.
> >
> > As you well know, Jerry, 5% is arbitrary.
> >
>
> It wasn't ironically and has nothing to do with 5%. As Marvin Zelen
> has pointed out, one-tailed tests are unethical from a human
> subjects perspective because they state that the difference can go
> in only one direction (we can argue about tests that are similar on
> the boundary, but I'm talking about how they are used in practice).
> If the investigator is *certain* that the result can go in only one
> direction, then s/he is ethically bound not to give a subject a
> treatment that is inferior to another.
>
> Consider yourself or someone near and dear with a fatal condition.
> You go to a doc who says, "I can give you A with P(cure) in your
> case of 20% or I can give you B for which P(cure) can't be less than
> 20% and might be higher. In fact, I wouldn't even consider B if
> there weren't strong reasons to suspect it might be higher. And
> let's not forget it can't be lower than 20%. I just flipped a
> coin. YOU CAN'T HAVE "B"!"
>
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--
Alan McLean ([EMAIL PROTECTED])
Department of Econometrics and Business Statistics
Monash University, Caulfield Campus, Melbourne
Tel: +61 03 9903 2102 Fax: +61 03 9903 2007
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