* Orange2 Example
  Formulate and test 2-way ANOVA models
  Use the class statement to indicate factors.
  proc anova could have been used instead of 
  proc glm;

data orange;
   infile "c:/datasets/orange.txt" firstobs=4;
   input variety $ pesticide $ yield;

proc print;

* Test additive model using null hypothesis
  model yield = variety;
proc glm;
   class variety pesticide;
   model yield = variety pesticide;

* Test whether interaction is significant
  using additive model for null hypothesis;
proc glm;
   class variety pesticide;
   model yield = variety pesticide variety*pesticide;

* Note: both proc glm runs automatically generate
  interaction plots;
 
run;
quit;