data a;
infile 'z:\stat 706\contrast.txt';
input percent strength;
/* Variables for Yandell approach */
plin=percent;
pquad=plin*plin;
/* And some other variables for an orthogonality  */
/* discussion                                     */
llin=(percent-25)/5;
lquad=llin*llin-2;
proc glm;
class percent;
model strength=percent;
contrast 'linear' percent -2 -1 0 1 2;
contrast 'quadratic' percent 2 -1 -2 -1 2;
contrast 'cubic' percent -1 2 0 -2 1;
contrast 'quartic' percent 1 -4 6 -4 1;
contrast 'linear and quadratic' percent -2 -1 0 1 2,
                                percent 2 -1 -2 -1 2;
contrast 'linear and quadratic lof' percent -1 2 0 -2 1,
                                    percent 1 -4 6 -4 1;
run;
/* Orthogonality demo   */
proc glm;
model strength=plin pquad;
run;
proc glm;
model strength=pquad plin;
proc glm;
model strength=llin lquad;
run;
proc glm;
model strength=lquad llin;
run;
/*Yandell approach*/
data b; set a;
plin=percent;
pquad=plin*plin;
proc glm;
class percent;
model strength=plin pquad percent/ss1;
run;