> At 09:55 AM 5/11/2007, Carola Weiss wrote:
> >I�m using the probit command to figure out the
> >impact of tenure to work satisfaction (binary
> >variable: 1= high work satisfaction).
> >I should estimate the marginal effects by using dprobit.
> >Can anybody tell me what�s he differnece? I
> >should only interpret significance and
> >direction of the effects. Therefore I only need the probit results,
> >don�t I?
--- Richard Williams <[email protected]> wrote:
> Why do you think you should only interpret
> significance and direction of effects? One of my
> pet peeves is that people do indeed often only
> look at sign and significance, and the
> practical/substantive significance remains
> unclear. Marginal effects are one way of getting at substantive
> significance.
I totally agree with Richard. Significant is not the same as relevant.
If I am in a bad mood I tell whomever comes in my office for help that
if they get a non-significant result that only means that they haven't
collected enough data, and if they get a significant result that they
collected too much data. Don't get me wrong, significance testing is a
very elegant and smart solution to an impossible problem, but too often
people attach magical properties to p-values. Just looking at some
predicted probabilities, marginal effects, or odds ratios (I am
actually starting to appreciate those, though I admit they are an
acquired taste) can tell you so much more. And don't forget graphs!!
Hope this helps,
Maarten
-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands
visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434
+31 20 5986715
http://home.fsw.vu.nl/m.buis/
-----------------------------------------
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