2007 National Roadside Survey of Alcohol and Drug Use by Drivers

2007 National Roadside Survey of Alcohol and Drug Use by Drivers: Drug ResultsTable 38. Drug Prevalence by Time of Day and BAC (Percentages Calculated by Row) (Oral Fluid)BAC (g/dL)Time of DrugNBetweenDay Result (Unweighted) Zero Zero and .08 .08+Positive 246 98.2% 1.4% 0.3%Daytime Negative 1,599 99.2% 0.6% 0.2%Overall Daytime 1,845 99.1% 0.7% 0.2%Positive 836 80.5% 15.0% 4.5%Nighttime Negative 5,031 90.2% 8.1% 1.7%Overall Nighttime 5,867 88.8% 9.1% 2.1%In this table, percentages are weighted.Table 39. Drug Prevalence by Time of Day and BAC (Percentages Calculated by Column)(Oral Fluid)BAC (g/dL)Time of DrugBetweenDay ResultZero Zero and .08 .08+ AllN=1,822 N=18 N=5 N=1,845Daytime Positive 10.9% 22.2% 17.1% 11.0%Negative 89.1% 77.8% 82.9% 89.0%N=5,207 N=530 N=130 N=5,867Nighttime Positive 13.1% 23.9% 30.6% 14.4%Negative 86.9% 76.1% 69.4% 85.6%In this table, “Ns” are unweighted and percentages are weighted.Table 40 shows that, within the daytime sample, drug-positive drivers in the age groups 16-20and 21-34 had the greatest percentage of alcohol-positive results; however, it should be notedthat the sample size for the youngest group was only 11. Among nighttime drug-positiveparticipants, drivers aged 21-34 had the greatest percentage of alcohol positives (in both thecategories BAC between zero and .08, and BAC .08+) (p < .01). As noted earlier, the number ofyears within age categories is not equivalent.54