cor(IX, IY) = 0.574
0.5
0.0
IX − IY
0.0
−0.5
−0.5
26%
0.5
1.0
1.5
IX − IY
74%
mean
2SN
0.0
Density
2.0
2.5
single
multiple
total
C
0.5
B
3.0
A
cor(IX, IY)=0.175
0.6
0.8
1.0
1.2
1.4
S(log(I))
1.6
1.8
0.6
0.8
1.0
1.2
(IX + IY)
1.4
2
1.6
0.6
0.8
1.0
1.2
(IX + IY)
1.4
2
1.6