Maarten,
Hmm, I think I understand where you are coming from, but by adjusting the constant in the equation, I consistently get the same values as _predict_... put another way, if I use the coefficients and constant given in the _fracpoly_ output, I get values that are always off of the _predict_ values by the same amount - and this can be fixed by adjusting the constant by the amount that I am off. This seems like a half-arsed way of doing things, I know, but it does seem to work.
--- Chris Witte wrote:
> I want to report the regression equation in my manuscript
> so the reader can plug in their independent variable values
> and get the correct estimate. I thought that calculating
> the difference between the _fracpred_ estimated values and
> the values estimated using the coefficients from the
> _fracpoly_ output would be the fastest way to find the
> "real" constant for reporting purposes. Is there a better
> (i.e. easier) way? Am I misunderstanding the process?
Point is that -fracpoly- does not adjust the constant but
the covariates. I would actually report the formulas in
a footnote or an appendix (together with the necessary
describtive statistics of the covariates, that are used
in the formulas). This way your result will become less
of a "black box".
-- Maarten
-----------------------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany
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