options nocenter ls=80 ps=50;
data a;
  infile 'drink.dat' firstobs = 2;
  input cow month first $ period dim water $ milk;
/* analyse first period only */
data c; set a;
  if period > 2 then delete;
proc mixed;
  class month cow first period water;
  model milk = first period water; 
  random cow(first);
proc mixed;
  class month cow first period water;
  model milk = month first period water; 
  random cow(month*first);
/* both periods */
proc mixed data=a;
  class month cow first water period;
  model milk = month period first water period*first*water first*month;
  random cow(month);
  lsmeans first*month;
/* drop unbalanced treatment combos */
data b; set a;
  if month = 2 then delete;
proc glm;
  class month cow first period;
  model milk= month cow(month) period first first*month / ss1 ss3;
  test h = month e = cow(month);
  lsmeans month / e=cow(month) stderr pdiff;
  lsmeans first first*month / stderr pdiff;