At 02:33 PM 9/13/01 +0100, Thom Baguley wrote:
>Rolf Dalin wrote:
> > Yes it would be the same debate. No matter how small the p-value it
> > gives very little information about the effect size or its practical
> > importance.
>
>Neither do standardized effect sizes.
agreed ... of course, we would all be a whole lot better off if a
researcher DEFINED for us ... a priori ... what size of effect he/she
considered to be important ... and why that "amount" has practical benefit
then we could evaluate (approximately) if he/she found something of
practical importance (at least according to the researcher)
but, what we get is an after the fact description of this .... which by the
very nature of its post hocness ... is not really that helpful
bringing into this discussion statistical significance only has relevance
IF you believe that null hypothesis testing is of real value
bringing effect size into the discussion only has relevance IF you know
what effect it takes to have practical importance ... (and i have yet to
see the article that focuses on this even if they do report effect sizes ... )
what we need in all of this is REPLICATION ... and, the accumulation of
evidence about the impact of independent variables that we consider to have
important potential ... and not to waste our time and money on so many
piddly manipulations ... just for the sake of "getting stuff published"
the recent push by apa journals and others to make submitters supply
information on effect sizes is, in my view, misplaced effort ... what
should be insisted upon in studies where the impacts of variables is being
investigated ... is a clear statement and rationale BY the researcher as to
WHAT size impact it would take to make a practical and important difference
...
if that ONE piece of information were insisted upon ... then all of us
would be in a much better position to evaluate results that are presented
reporting effect sizes (greater than 0) does nothing to help readers
understand the functional benefit that might result from such treatments
until we tackle that issue directly, we are more or less going around in
circles
>Thom
>
>
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_________________________________________________________
dennis roberts, educational psychology, penn state university
208 cedar, AC 8148632401, mailto:[EMAIL PROTECTED]
http://roberts.ed.psu.edu/users/droberts/drober~1.htm
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