Live is not simple. The term "observed significance level" or "achieved
significance level" is fairly standard in statistics. It's basically
the p-value. For a precise definition, see Efron and Tibshirani,
Introduction to the Bootstrap, p. 203.
The quotation of A. Lincoln merely gives one side in the age-old
realism - nominalism debate. H. Dumpty would disagree.
At 2:49 PM -0500 1/29/00, Donald F. Burrill wrote:
>On Sat, 29 Jan 2000 [EMAIL PROTECTED] wrote:
>
> > In a message dated 1/29/2000 1:54:04 PM Eastern Standard Time,
> > [EMAIL PROTECTED] writes:
> >
> > > Of course not. Significance level cannot be computed: it is an
> > > arbitrary choice of the investigator (or the analyst).
> >
> > I think there is a semantical misunderstanding here.
>
> Precisely. That was the point of my response.
>
> > Significance level may be computed for a given numerator degrees of
> > freedom, denominator degrees of freedom, and observed value of F.
>
>This is not true. What you can COMPUTE is the probability that the
>observed value of F (or greater) would occur if the null hypothesis
>(of no differences among any of the population means, which is consistent
>with an F value of 1) were true.
>
> > Generally, investigators set a significance level which their, say,
> > regression coefficients must meet. That's different.
>
>No, it is not. Same principle, applied to different parameters.
>
> > I found several web pages which compute significance level. For
> > example, see site http://www.cytel.com/statable/
>
>You can find all sorts of damfool things in the world if you look hard
>enough. That you found one (or even several) doesn't mean it's right.
>Even respected statistical packages err on this point: SPSS, for
>example, routinely uses the label "Sig." when what is reported is "p".
> What these routines compute is not in fact significance level, it is the
>observed probability value corresponding to the value of F (or t, or z,
>or whatever) one supplies. Useful only for determining whether a
>particular result meets the significance level chosen by the investigator
>or analyst.
> I am reminded of the conundrum attributed to A. Lincoln:
>"If you call a tail a leg, how many legs does a horse have?" His answer:
>"Four. Calling a tail a leg doesn't make it one."
> Just so.
> -- DFB.
> ------------------------------------------------------------------------
> Donald F. Burrill [EMAIL PROTECTED]
> 348 Hyde Hall, Plymouth State College, [EMAIL PROTECTED]
> MSC #29, Plymouth, NH 03264 603-535-2597
> 184 Nashua Road, Bedford, NH 03110 603-471-7128
>
>
>
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Jan de Leeuw; Professor and Chair, UCLA Department of Statistics;
US mail: 8142 Math Sciences Bldg, Box 951554, Los Angeles, CA 90095-1554
phone (310)-825-9550; fax (310)-206-5658; email: [EMAIL PROTECTED]
http://www.stat.ucla.edu/~deleeuw and http://home1.gte.net/datamine/
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This list is open to everyone. Occasionally, people lacking respect
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