options
ps=60
ls=80
pageno=1
formdlim='_';
data
chemical;
input
yield alcohol $ base $;
cards;
91.3 a1 b1
91.4 a1 b1
89.9 a1 b1
94.4 a1 b1
90.7 a1 b2
94.7 a1 b2
89.5 a1 b2
85.2 a1 b2
89.9 a2 b3
92.3 a2 b3
92.6 a2 b3
94.4 a2 b3
88.1 a2 b4
93.1 a2 b4
90.8 a2 b4
98.1 a2 b4
79.5 a3 b5
70.1 a3 b5
79.7 a3 b5
76.1 a3 b5
87.6 a3 b6
89.8 a3 b6
88.2 a3 b6
87.7 a3 b6
;
/* The convention to specify a nested factor in SAS is to use B(A); that is,
B is nested within A. */
proc
glm;
class
alcohol base;
model
yield = alcohol base(alcohol);
means
alcohol base(alcohol);
lsmeans
base(alcohol)/pdiff
cl;
/*gives all possible
pairwise intervals */
run;
/* Since B(A) is significant, let's compare the means of B within each level
of A */
proc
glm;
class
alcohol base;
model
yield = alcohol base(alcohol);
contrast
'b2-b1 within a1'
base(alcohol) -1
1
0
0
0
0;
contrast
'b4-b3 within a2'
base(alcohol) 0
0
-1
1
0
0;
contrast
'b6-b5 within a3'
base(alcohol) 0
0
0
0
-1
1;
run;
/* Had base (B) not been significant, we could have pushed forward by
comparing the levels
of alcohol (A). Note that since B really is significant, the analysis below is
almost
meaningless. */
proc
glm;
class
alcohol base;
model
yield = alcohol base(alcohol);
lsmeans
alcohol/pdiff
cl;
run;