--- [email protected] wrote:
> Does anyone have any recommendations for creating a quadratic spline
> plot with one knot?
*------------------ begin example ----------------------
sysuse nlsw88, clear
// create quadritic spline
sum hours
gen zhours = (hours - r(mean))/r(sd)
mkspline shours 2 = zhours, marginal
replace shours1 = shours1^2
replace shours2 = shours2^2
// estimate logit model
logit union zhours shours1 shours2 south tenure
// create graph of predicted probability
// for people from the with mean tenure
adjust south=0 tenure, by(hours) pr ci replace
twoway rarea lb ub hours || line pr hours, legend(off)
*------------------- end example ------------------------
(For more on how to use examples I sent to the Statalist, see
http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html )
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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