Analysis of data from a single human platelet Toolkit binding experiment. The bars show the number of occurrences of any given absorbance value in the dataset (a total of 64 values, one for each adhesion substrate). The dashed line illustrates model no. 1 in which the data are represented as a single normal distribution. The dotted line illustrates model no. 2 in which the data are represented as 2 independent normal distributions, one for nonresponders (mean ± SD = 0.15 ± 0.018) and one for responders (0.65 ± 0.30). In this example, the data clearly conform to model no. 2 better than to model no. 1 (P < .001), and 21 of 64 data points were determined to be responders.