/* chex51.sas                             */
 /* Example 5.1 -- condition of regression */
 /*  problem for changes in y              */
  options ls = 80 ;                        * easier to read output ;
  data a ;
    input x y ystar ;
    cards ;
  1.0  0.9   0.90
  1.0  1.0   0.99
  1.1  1.0   1.01
  1.1  1.1   1.10
 ;
 run ;
 /* include both y and ystar in model      */
 /*  statement -- no change in x           */
 /*                                        */
  proc reg data=a ;
    model y ystar = x / r ;
    title 'Chex51.sas condition of regression' ;
 run ;