
222 Statistics and Data Analysis for Microarrays Using R and Bioconductor
−1.5 −1.0 −0.5 0.0 0.5 1.0
−3 −2 −1 0 1 2
x
y2
FIGURE 8.2: An example of two var iables that have a medium p ositive
correlation.
−1.5 −1.0 −0.5 0.0 0.5 1.0
−2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0
x
y3
FIGURE 8.3: An example of two variables that have a high positive cor re-
lation.