V.  RESULTS AND DISCUSSION

Connecticut Roadside Survey

G. Direct Observations of Driver BACs

BACs were measured from drivers agreeing to take a blind, anonymous breath test.  As presented in Table 27, there was an increase in the number of drinking drivers after the July 4th holiday period that was consistent with the self-reports of drinking and driving.  More than three times as many sobriety checkpoints were held during the winter holiday period and were preceded by many more sobriety checkpoints during the sustained enforcement period that extended from summer to fall, so the cumulative effect of the campaign on driver BACs requires comparing the pre-July 4th data to the post-winter holiday period data.  There are differences in the locations and times of night when comparing the pre-July 4th holiday period BACs to the post-winter holiday period BACs.  However, in looking at the overall impact of the program from its inception to its peak, there was a significant decrease in the proportion of drivers with a positive BAC compared to those with a zero BAC from the pre-July 4th period to the post-winter holiday enforcement period (χ²(1)=7.015, p≤.01).  The pre-July 4th holiday sobriety checkpoints and post-winter holiday sobriety checkpoints were both conducted during colder, non-holiday times of the year and, as indicated in Table 28, the breath test refusal rates were very similar for both of these survey periods.

A comparison of the positive BACs from the pre- and post-winter holiday periods indicated that the proportion of positive BACs decreased while the proportion of zero BACs increased.  In addition, there was a significant decrease in the refusal rate when comparing the pre-winter holiday period to the post-winter holiday period (χ²(1)=4.29, p<.04).  Both sets of results are presented in Table 27 and Table 28. 

The winter holiday data for both pre- and post- surveys were matched by times of night for each matching location.  All things being equal, the refusal rate should be consistent across conditions because drivers generally refuse the survey for the same reasons across time or may even refuse more often if drivers keep encountering sobriety checkpoints on the same road they travel frequently.  However, when drivers refuse because they have a positive BAC, the proportion of refusals would be expected to change as the number of drivers with a positive BAC changed.  In fact, the refusal rate decreased significantly after the winter holiday campaign crackdown compared to the fall before the crackdown.  The decrease may mean that the same proportion of drivers refusing because of the time required and intrusiveness of the survey, but the number of drivers with a positive BAC went down, resulting in the significant decrease in refusals.  If the refusal proportions are combined with the proportion of those with known positive BACs in each condition, the result is a significant decrease from 20.2 percent to 16.2 percent after the winter holiday period compared to the pre-winter holiday period (χ²(2)=6.70, p<.04).

Table 27. Connecticut Roadside Survey: Driver BACs and Refusals

Table 28. Connecticut Roadside Survey: Breath Test Refusal Rates

There were no statistically significant changes in the proportion of men 16 to 34 with positive BACs after either the July 4th holiday period (χ²(1)=2.89, p>.05) or the winter holiday period (χ²(1)=.540, p=.463) when compared to each pre-holiday period.  As shown in Table 29, there was an overall decrease of 4.8 percent in the proportion of men 16 to 34 with positive BACs.  However, the decrease was not statistically significant (χ²(1)=2.886, p, ≤.10).  As presented in Table 30, there were no significant changes in the refusal rates of men 16 to 34 after either holiday enforcement period.

Table 29. Connecticut Roadside Survey: Men 16 to 34 Driver BACs and Refusals

Table 30. Connecticut Roadside Survey: Men 16 to 34 Breath Test Refusal Rates