/* module 9: */

/* 9: 1 */

data one;
  do i = 1 to 20;
    x = rannor(1234);
    x1=x*10;
    x2=(2*i)+(x*3);
    x3=((i-10.5)**2) +x*9;
    output;
  end;
run;

data two;
  set one;
  t=i;
  x=x1;
  y=x2;
  z=x3;
  keep t x y z;
run;
proc print data=two;
run;

proc plot data=two;
  plot x*t;
  plot y*t;
  plot z*t;
run;
* x has no relation to t; y has a positive linear term in t;
* z has a positive parabolic term in t; so y is correlated;
* positively to t, and x and z aren't, and the calculations;
* below bear that out;

/* 9: 2 */

proc corr data=two;
  var  x t;
run;

proc corr data=two;
  var  y t;
run;

proc corr data=two;
  var  z t;
run;