Figure 2:
The lower triangular portion of the figure contains pie charts of the Pearson’s correlation coefficient between any pair of measures after binarizing them. Completely filled pie chart indicates a correlation of 1 (when blue) or −1 (when orange). Partially filled pie charts, the direction of fill indicates the sign (positive for clockwise and negative for correlation) of correlation and the proportion indicates the values. Additionally, colors of the pie chart are bluish for high positive correlation and orangish for low correlation (positive or negative).