sas 공부하는 중인데  

data ex10_3;

input food $ lab mat @@;
cards;
A 1 3.4 A 2 3.0 A 3 3.3 A 4 3.5
B 1 2.6 B 2 2.7 B 3 3.0 B 4 3.1
C 1 2.8 C 2 3.1 C 3 3.4 C 4 3.7
;
run;

proc anova data=ex10_3;
class food lab;
model mat = food lab
                          food*lab ;
means food lab food*lab ;
run;

하면  유의확률값이 .으로 나오는데 왜 그런거임?
뭐라고 해석해야함?