Non-Indexed and indexed 24-hour post-op bleeding. Non-indexed (a) and indexed (b) total chest tube outputs of 24hr post-op of the three groups are shown as box and whisker plots. p values of the chi-square test of independence of the non-indexed median (a) between any two groups are greater than 0.05 (Table 2). P-value of the chi-square test of independence of the non-indexed median (a) between 1.0 and 0.8 is 0.14 while that of the indexed (b) is 0.02 (Table 2). Outliers greater than 2500 ml (a) and 1200 ml (b) are not shown, respectively.