Scatterplot of VWF:Ag (Ag), VWF:RCo (RCo), and VWF:RCo/VWF:Ag ratio (ratio) for all African American (AA; ●) and Caucasian controls (CA; ○) enrolled in the ZPMCB-VWD. The mean value for each assay is shown at the top of the graph for 59 African American and 113 Caucasian healthy controls. Error bars represent ± 1 SD.