#delim cr
version 6.0
/*
 Examples for the STB bulletin submission for bspline and frencurv
*/

/* Open log file */
log using example1.log,replace
capture noisily{
/* Beginning of main capture block */

/* Use auto data set and define additional variables */
use auto,clear
sort weight
desc
/* Create symbol variable for foreign cars */
gene str1 forsym="D"
replace forsym="F" if(foreign)

/*
 Demo of frencurv and bspline
*/

* frencurv with extended reference points (default) and cubic spline *
frencurv,xvar(weight) refpts(1760(770)4840) gen(cs) power(3)
describe cs*
regress mpg cs*,noconst robust
lincom cs3-cs5
predict mpghat3
grap mpg mpghat3 weight,s(o.) c(.L) xlab(1760(770)4840) ylab(0(5)45) t1(" ") l1("Mileage (mpg)") saving(fig3.gph,replace)

* frencurv with cubic spline and unextended reference points *
frencurv,xvar(weight) refpts(1760(513.33333)4840) noexr k(1760(770)4840) gen(sp) power(3) labfmt(%7.2f)
describe sp*
regress mpg sp*,noconst robust

* bspline with the same model as frencurv *
bspline,xvar(weight) knots(1760(770)4840) gen(bs) power(3) labf(%4.0f)
describe bs*
regress mpg bs*,noconst robust

/*
 Convert Stata graphics to encapsulated PostScript
 (USING THE gphpen ROUTINE FOR WINDOWS,
 WHICH I HAVE BUT MOST Stata 6.0 USERS DO NOT HAVE)
*/
gphpen /n /deps /ofig3.eps fig3.gph

/* End of main capture block */
}
/* Close log file and exit */
log close
exit