Actually, it should be:
proc glm data=data;
class day;
model TimeSpent = day;
lsmeans day / pdiff;
run;
Note: you may have clustering with your data, if you are recording/measuring the same individuals at each of these times (a type of repeated measures). That is, with three values per subject (I call it id here). Would have to know more information, but you could handle in a simple way, if
proc mixed data=data;
class id day;
model TimeSpent = day;
random id;
lsmeans day / pdiff;
run;
... View more