Figure 1 shows the empirical relationship between self-reported volume (x-axis) and BAC (y-axis) for all respondents (the individual-level relationship) and indicates substantial variability between the two measures. Note that BAC is measured in milligrams/deciliter (mg/dl) so that, for example, a BAC concentration of .08%= 80 mg/dl. Figure 2 shows averaged BAC values for each of a number of categorized self-reported volume levels VSR (the aggregate-level relationship) and indicates a steep initial rise in BAC (up to about 7 self-reported drinks) followed by a leveling off above (starting above about 7 drinks) with increasing variability in the average value.
