Documentation Example 1 for PROC NLIN
/****************************************************************/
/* S A S S A M P L E L I B R A R Y */
/* */
/* NAME: nlinex1 */
/* TITLE: Documentation Example 1 for PROC NLIN */
/* Segmented Model */
/* PRODUCT: STAT */
/* SYSTEM: ALL */
/* KEYS: Reparameterization */
/* Continuity condition */
/* Smoothness condition */
/* PROCS: NLIN, SGPLOT */
/* DATA: */
/* */
/* SUPPORT: Oliver Schabenberger */
/* REF: */
/* MISC: */
/****************************************************************/
data a;
input y x @@;
datalines;
.46 1 .47 2 .57 3 .61 4 .62 5 .68 6 .69 7
.78 8 .70 9 .74 10 .77 11 .78 12 .74 13 .80 13
.80 15 .78 16
;
title 'Quadratic Model with Plateau';
proc nlin data=a;
parms alpha=.45 beta=.05 gamma=-.0025;
x0 = -.5*beta / gamma;
if (x < x0) then
mean = alpha + beta*x + gamma*x*x;
else mean = alpha + beta*x0 + gamma*x0*x0;
model y = mean;
if _obs_=1 and _iter_ =. then do;
plateau =alpha + beta*x0 + gamma*x0*x0;
put / x0= plateau= ;
end;
output out=b predicted=yp;
run;
proc nlin data=a;
parms alpha=.45 beta=.05 gamma=-.0025;
x0 = -.5*beta / gamma;
if (x < x0) then
model y = alpha+beta*x+gamma*x*x;
else model y = alpha+beta*x0+gamma*x0*x0;
run;
proc nlin data=a;
parms alpha=.45 beta=.05 gamma=-.0025;
x0 = -.5*beta / gamma;
model y = (x =x0)*(alpha+beta*x0+gamma*x0*x0);
run;
proc sgplot data=b noautolegend;
yaxis label='Observed or Predicted';
refline 0.777 / axis=y label="Plateau" labelpos=min;
refline 12.747 / axis=x label="Join point" labelpos=min;
scatter y=y x=x;
series y=yp x=x;
run;
proc nlin data=a;
parms alpha=.45 beta=.05 x0=10;
if (x