--- I wrote:
> An even better and easier way to get
> such a combined estimate is to constrain the effect of
> explanatory variable to be the same across years. This is
> actually very simple to do, since all you have to do is
> *not* add an interaction term with year.
A detailed description of interaction effects and lots of
Stata examples can be found on:
http://www.ats.ucla.edu/stat/stata/webbooks/reg/chapter3/statareg3.htm
http://www.ats.ucla.edu/stat/stata/webbooks/reg/chapter6/statareg6.htm
HTH,
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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