Scatter plots and correlation coefficients r_xy (from Eq. (C.1)) between the velocity-integrated intensity of ¹²CO and ¹³CO J = 1 → 0 (top-left), and the ¹²CO J = 2 → 1 compared to the J = 2 → 1 lines of ¹³CO (top-right), CO (middle-left), and CO (middle-right). The bottom panel shows the scatter plot and correlation coefficient between the [C I] 370 μm and the J = 2 → 1 transitions of ¹³CO (bottom-left) and CO (bottom-right).