At 12:14 PM 1/31/01 +1100, Alan McLean wrote:
>For hypothesis testing there does have to be a null model - that is the
>first feature that identifies hypothesis testing from other forms of
>model selection.
check
>
>A hypothesis test is only carried out if the sample data disagrees with
>the null. If it is a point null (eg mu = 20) this is almost guaranteed.
>The p value is essentially a measure of the level of disagreement
>between the sample data and the null. If p is low, there is strong
>agreement, if p is high there is weak disagreement.
>
>So I agree that your interpretation is reasonably correct.
phew ... thanks (at least so far)
>
>BUT - the p value still does not say anything about the actual value -
>only about the level of disagreement between what the null says it
>should be and the sample says it should be.
well, since there are a zillion different possible nulls ... then sure
but, in a given context there are not a zillion nulls ... only 1 (i assume)
... like, mu = 90 ... or, rho = .7 ... or sigma squared = 256
and since the null in a context is a constant ... but, the sample could be
telling you varying things ... what we have is a difference value ...
between a variable and a constant ... and while your argument seems to
focus on the actual "difference" value ... it is not a floating difference
at both ends ... only ONE end ... the sample end ... so, in fact, the
difference value will lead you to that constant ... even if the variable
(sample value) is moving ... which leads you right back to THAT null value
so, if that is the case ... and while you might say that if the null had
been mu = 90 and ... a given p is attached to that test ... that the p says
nothing about THAT particular null ... would i be correct in saying that
the p says something therefore about 91 ... or 87 ... or NO value?
you might be technically correct ... and, if you want, i will concede that
you are ... but, the practical distinction you are making escapes me ...
if the p doesn't say something about the null you have posited ... i am
wondering what the use of positing that null was in the first place and,
then ... what help p is really bestowing upon you (whether it be p=.09 or
.03 or .008?) with respect to that posited null
i can't wait to try to make this distinction to my students ...
>
>Alan
>
>> >
>> >
>> >> _________________________________________________________
>> >> dennis roberts, educational psychology, penn state university
>> >> 208 cedar, AC 8148632401, mailto:[EMAIL PROTECTED]
>> >> http://roberts.ed.psu.edu/users/droberts/drober~1.htm
>> >>
>> >> =================================================================
>> >> Instructions for joining and leaving this list and remarks about
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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
>>
>> ==============================================================
>> dennis roberts, penn state university
>> educational psychology, 8148632401
>> http://roberts.ed.psu.edu/users/droberts/drober~1.htm
>
>--
>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
==============================================================
dennis roberts, penn state university
educational psychology, 8148632401
http://roberts.ed.psu.edu/users/droberts/drober~1.htm
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Instructions for joining and leaving this list and remarks about
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