Patterns of variability in cohort 1. (A) Correlation matrix summarizing patterns between the 12 measures of platelet function and the sensitivity and capacity of fibrinogen and P-selectin to the agonists ADP, CRP, and TRAP-6. The area, shape, and color of the ellipses correspond to Spearman’s correlation coefficient. Colors indicate Spearman’s correlation coefficient values ranging from −1 (dark red) to +1 (dark blue). The ellipse shape indicates the relative spread of data points and the slope of the correlation, with a wider ellipse indicating a greater relative spread and a narrower ellipse indicating a lower spread (numerical values for Spearman correlation coefficients are given in supplemental Figure S12. (B) Examples of concentration-response curves for 4 donors. The curves depicted in red and magenta have capacity and sensitivity that correlate (high and low, respectively), whereas response curves in blue and gray do not follow this pattern and have high sensitivity but low capacity and vice versa. All curves are for P-selectin in response to CRP. (C) Effects of platelet inhibitors (100 µM aspirin, 1 µM cangrelor, or both) on responses to ADP, CRP, and TRAP-6. Data are generated from the responses of 10 blood donors. (D-E) Results of the PCA (scree plot is provided in supplemental Figure 18). The biplots show vectors representing each variable on a plane where the angle between the vectors is informative; vectors closer together suggest dependence, whereas those that are orthogonal suggest a lack of independence in the variables. (D) Biplot of PC1 and PC2. (E) PCA biplot of PC1 (x-axis) and PC3 (y-axis). In both biplots, colored arrows represent the contribution of each variable to the PC; arrows representing measures of sensitivity are shown in red, and arrows representing measures of capacity shown in blue.