Time of arrival was used instead of time of BAC to calculate the variable H as it allowed the inclusion of additional data (i.e., for some studies/individuals, time of BAC was not available or missing). For those cases with both time of arrival and time of BAC (87% of the total used in this analysis), about 75% of the cases had time between arrival and BAC of less than 30 minutes, 90% less than 1 hour, and 98% less than 2 hours. Therefore, this difference should not significantly affect calculation of BAC using the Widmark method.
