Wouldn't you learn the same thing with a confidence interval on rho?
Jon Cryer
At 02:19 PM 4/10/00 -0400, you wrote:
>Seems to me that hypothesis testing remains an essential step. Take for
>instance the following data that I made up just for the purpose of
>illustration and the correlation matrix it produces:
>
>VAR1 VAR2
>2.00 2.00
>3.00 2.00
>5.00 6.00
>4.00 2.00
>3.00 1.00
>
>Correlations
> VAR1 VAR2
>VAR1
>Pearson Correlation 1.000 .765
>Sig. (2-tailed) . .132
>N 5 5
>
>VAR2
>Pearson Correlation .765 1.000
>Sig. (2-tailed) .132 .
>N 5 5
>
>
>Now, .77 is probably a respectable correlation (depending of course on the
>application). However, the question here is how much faith we have in this
>estimate. Accepting the traditional alpha level of .05 (because it is not
>real data and so no reason not to) we would say that this is beyond what we
>will accept as the risk of making a Type I error, so we fail to reject the
>null. This is not to say that the correlation is zero, but for practical
>purposes with this sample, we must treat it as no effect (and here probably
>take into consideration our power). Effect size is useless without
>significance. Significance is meaningless without information on effect
>size.
>
>
>
>
>-----Original Message-----
>From: dennis roberts [mailto:[EMAIL PROTECTED]]
>Sent: Monday, April 10, 2000 1:35 PM
>To: [EMAIL PROTECTED]
>Subject: Re: hyp testing
>
>
>At 01:16 PM 4/10/00 -0300, Robert Dawson wrote:
>
>>both leave the listener wondering "why 0.5?" If the only answer is "well,
>>it was a round number close enough to x bar [or "to my guesstimate before
>>the experiment"] not to seem silly, but far enough away that I thought I
>>could reject it." then the test is pointless.
>>
>> -Robert Dawson
>
>
>YOU HAVE made my case perfectly! ... this is why the notion of hypothesis
>testing is outmoded, no longer useful ... not worth the time we put into
>teaching it ...
>in the case above ... i would ask:
>
>what is the population rho value ... THAT is the important inferential
>issue ...
>
>there is no reason why we would have to say: i wonder if it is .5 ... let's
>TEST that, or ... i wonder if it is .7 ... let's TEST that ...
>
>we can simply ask the question and try to get an answer to that ... and
>there is no need to test a pre formulated null to get some sensible answer
>to the question
>
>no need for ANY null ... therefore no need for any hypothesis test
>
>if 0 is absurd ... and, if i hypothesized .5 and you ask why .5??? then we
>could have asked anywhere from 0 to .5 ... and they would have been just as
>non functional ...
>
>that's it ... hypothesis testing is non functional
>
>
>
>
>
>
>
>
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_____________
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Jon Cryer [EMAIL PROTECTED] ( )
Department of Statistics http://www.stat.uiowa.edu\ \_ University
and Actuarial Science office 319-335-0819 \ * \ of Iowa
The University of Iowa dept. 319-335-0706 \ / Hawkeyes
Iowa City, IA 52242 FAX 319-335-3017 |____________ )
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