At 08:46 AM 4/20/01 +1000, Alan McLean wrote:
>So the two good reasons are - that the z test is the basis for the t,
>and the understanding that knowledge has a very direct value.
>
>I hasten to add that 'knowledge' here is always understood to be
>'assumed knowledge' - as it always is in statistics.
>
>My eight cents worth.....
>
>Alan
the problem with all these details is that ... the quality of data we get
and the methods we use to get it ... PALE^2 in comparison to what such
methods might tell us IF everything were clean
DATA ARE NOT CLEAN!
but, we prefer it seems to emphasize all this minutiae .. rather than spend
much much more time on formulating clear questions to ask and, designing
good ways to develop measures and collect good data
every book i have seen so causally says: assume a SRS of n=40 ... when SRS
are nearly impossible to get
we dust off assumptions (like normality) with the flick of a cigarette ash ...
we pay NO attention to whether some measure we use provides us with
reliable data ...
the lack of random assignment in even the simplest of experimental designs
... seems to cause barely a whimper
we pound statistical significance into the ground when, it has such LIMITED
application
and the list goes on and on and on
but yet, we get in a tizzy (me too i guess) and fight tooth and nail over
such silly things as should we start the discussion of hypothesis testing
for a mean with z or t? WHO CARES? ... the difference is trivial at best
in the overall process of research and gathering data ... the process of
analysis is the LEAST important aspect of it ... let's face it ... errors
that are made in papers/articles/research projects are rarely caused by
faulty analysis applications ... though sure, now and then screw ups do
happen ...
the biggest (by a light year) problem is bad data ... collected in a bad
way ... hoping to chase answers to bad questions ... or highly overrated
and/or unimportant questions
NO analysis will salvage these problems ... and to worry and agonize over z
or t ... and a hundred other such things is putting too much weight on the
wrong things
AND ALL IN ONE COURSE TOO! (as some advisors are hoping is all that their
students will EVER have to take!)
>--
>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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==============================================================
dennis roberts, penn state university
educational psychology, 8148632401
http://roberts.ed.psu.edu/users/droberts/drober~1.htm
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