Use the PLOTS(INTERPOLATE) Option in PROC TRANSREG

/****************************************************************/
/*          S A S   S A M P L E   L I B R A R Y                 */
/*                                                              */
/*    NAME: tregint                                             */
/*   TITLE: Use the PLOTS(INTERPOLATE) Option in PROC TRANSREG  */
/* PRODUCT: STAT                                                */
/*  SYSTEM: ALL                                                 */
/*    KEYS: regression analysis, transformations                */
/*   PROCS: TRANSREG                                            */
/*    DATA:                                                     */
/*                                                              */
/* SUPPORT: saswfk                UPDATE: July 25, 2010         */
/*     REF: PROC TRANSREG, DETAILS, INTERPOLATE                 */
/*    MISC:                                                     */
/****************************************************************/

title 'Smoother Interpolation with PLOTS(INTERPOLATE)';

data a;
   input c y x;
   output;
   datalines;
1 1 1
1 2 2
1 4 3
1 6 4
1 7 5
2 3 1
2 4 2
2 5 3
2 4 4
2 5 5
;


ods graphics on;

proc transreg data=a plots=(tran fit) ss2;
   model ide(y) = pbs(x) * class(c / zero=none);
run;

data b;
   set a end=eof;
   output;
   if eof then do;
      y = .;
      do x = 1 to 5 by 0.05;
         c = 1; output;
         c = 2; output;
      end;
   end;
run;

proc transreg data=b plots(interpolate)=(tran fit) ss2;
   model ide(y) = pbs(x) * class(c / zero=none);
run;