Figure 2

Error-weighted similarity examples. The figures (A) and (B) depict examples when error-weighted similarity (Eq. (1) in the text) is problematic as a correlation measure. (A) A scatter plot of the expression profiles for two genes g5 and g6 (with 3 components), g5 = (100, 300, 400) and g6 = (100, 300, 400). The plotted expression profiles fall exactly on a straight line, however the error-weighted similarity ${\tilde{\rho }}_{5,6}$ for these genes is only 0.79 when 05 = (10, 15, 50) and σ 6 = (30, 50, 15). (B)A scatter plot of the expression profiles for two genes g7 and g8 (with 3 components), g7 = (100, 300, 400) and g8 = (100, 400, 300). The plotted expression profiles do not fall on a straight line, however the error-weighted similarity ${\tilde{\rho }}_{7,8}$ for these genes is 1.0 when 01 = (20, 20, 50) and σ 8 = (20, 50, 20).