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Re: st: RE: Graphing ploynomial relationships after a regression


From   n j cox <n.j.cox@durham.ac.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: Graphing ploynomial relationships after a regression
Date   Tue, 18 Oct 2005 16:48:32 +0100

Even with Maarten's example, things can be made
simpler. Starting as before,

sysuse auto, clear
gen weight2 = weight^2
reg price weight weight2

if you

predict quad
twoway mspline quad weight || scatter price weight

you get the data shown as well.

Alternatively, if you install the -modeldiag- package
from either SSC or the Stata website, then

predict quad
regplot

will give you the same graph. This is because -regplot-
defaults to a plot of the observed and predicted response
against the first predictor named.

Maarten Buis

sysuse auto, clear
gen weight2 = weight^2
reg price weight weight2
sum weight
twoway function y = _b[_cons]+_b[weight]*x+_b[weight2]*x^2, range(1760 4840)


Tinna

I am using an independent variable in its regular and squared forms in
an OLS and 2SLS regressions.  Can I graph this polynomial relationship
as indicated by the regression in an easy way?
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