Results of Data on DUI Arrests

Data on the number of DUI arrests in each county before and after implementation of the program in 2002 were examined to determine if the number of impaired driving arrests increased or decreased and whether the Extra Eyes program may have influenced the increase or decrease. Data for our analysis of annual arrests for alcohol-related violations from 2000 to 2003 were obtained from the Maryland Motor Vehicle Administration. Data for 2004 were available only through May, so they were not were not used in the analysis. The data are plotted in Figure 5.

Figure 5. Annual Arrests for Alcohol-Related Violations by County

Table 12 reports the number of DUI arrests made on the nights of Extra Eyes activities. Unfortunately, only 2002 and 2003 data can be compared with Figure 5. During the first year of the Extra Eyes program (2002), 16 DUI arrests were made. This number tripled the second year (2003) of the program to 48 DUI arrests. Inversely, arrests across Montgomery County during the entire year (not exclusively Extra Eyes occasions) slightly decreased from almost 2,500 in the year 2002 to approximately 2,250 in the year 2003 (this countywide pattern is discussed in detail below). The decrease in arrests may be due to the burn-out and officer shortage that was reported that year because of the 9/11 tragedy and the Washington Metropolitan area sniper. Arrests in the comparison sites also decreased. They too, were affected by these two events. Finally, the Extra Eyes program began in the winter of 2002, thus it is difficult to determine its impact. However, it is clear that the direct program arrests emanating from an effort as small as Extra Eyes is unlikely to significantly affect countywide DUI arrest statistics in a jurisdiction of this size.

Table 12. Number of DUI Arrests Made During Extra Eyes Occassions in Montgomery County, Maryland

Analytic Procedures

To analyze State arrest data, chi-squared tests were used to determine whether there was independence (no interaction) between the years and the number of arrests experienced by Montgomery County and the comparison counties (Anne Arundel and Prince George’s). Specifically, we examined whether any decline observed in the arrests in Montgomery County in 2003 (the year after the intervention of November 2002) was significant in the presence of any changes occurring in the other counties.

The data were analyzed in six ways: Montgomery County versus the comparison counties (separately and combined) by three variations of the years (individual years, 2000–2002 pooled vs. 2003, and 2002 vs. 2003). The results are presented in Tables 13 through 18.

Results

The plots in Figure 5 clearly show that annual DUI arrests in the three counties declined from 2000 to 2003. For Montgomery County (MC), there was a 15 percent decrease from 2000 to 2001, no change from 2001 to 2002, and a 9 percent decrease from 2002 to 2003. For Anne Arundel County (AAC), there was an 8 percent decrease from 2000 to 2001, a 1 percent decrease from 2001 to 2002, and no change from 2002 to 2003. For Prince George’s County (PGC), there were constant annual declines of 13 percent from 2000 to 2002, and a 7 percent decline from 2002 to 2003.

Table 13 presents annual arrests by county from 2000 to 2003. Analysis of these data shows that there is dependence between the year and county (χ² = 32.4, p < 0.001). Table 14 presents data combining the comparison counties, and these results indicate that there was only marginal dependence (χ² = 6.4, p = 0.09).

Table 13. Arrests by Year and County—All Years and Counties Separate

Table 14. Arrests by Year and County—All Years with Anne Arundel and Prince George’s Counties Combined

The results presented in Tables 15 and 16 pertain to the analysis of Montgomery County versus the comparison counties, both individually and combined, with the years from 2000 to 2002 combined (pre-period) versus 2003 (post-period). These results are similar to those presented previously, where the individual years were analyzed; with the counties separated, there is an interaction between county and time-period (χ² = 17.9, p < 0.001) and nonsignificant interaction when the counties are combined (χ² = 3.1, p = 0.08).

^{Table 15. Arrests by Year and County (2000 to 2002 Combined and 2003), with Counties Separate}

^{Table 16. Arrests by Year and County (2000 to 2002 Combined and 2003), with Anne Arundel and Prince George’s Counties Combined}

The results presented in Tables 17 and 18 pertain to the analysis of Montgomery County versus the comparison counties, both individually and combined, with only 2002 (pre-period) and 2003 (post-period) being analyzed. With the counties separated, there is only marginal interaction (χ² = 5.0, p = 0.08); there also is marginal interaction with the counties combined (χ² = 3.4, p = 0.07).

Table 17. Arrests by Year and County (2002 and 2003 Only), with Counties Separate

Table 18. Arrests by Year and County (2002 and 2003 Only), with Anne Arundel and Prince George’s Counties Combined

These results confirm that the annual DUI arrests in each of the three counties decreased from 2000 to 2003. When the counties were analyzed separately, however, there was significant time (or time-period) by county interaction, which occurred mainly because both Montgomery and Prince George’s counties had significant decreases over time. When the comparison counties were combined, the time (time-period) by county group interaction was only marginally significant. When the 2002 arrests were compared with 2003 arrests, the time-by-group interaction was only marginally significant, both when the counties were analyzed separately and when they were combined.

One may conclude that the decrease in the number of alcohol-related arrests in Montgomery County may not be attributed to Extra Eyes for two reasons: there was a decrease in the number of alcohol-related arrests in Montgomery County before the intervention, and there was a similar decrease in alcohol-related arrests in Prince George’s County (a comparison county) after the intervention. Conversely, it is clear that there was no increase in the arrests in Montgomery County due to the Extra Eyes program.

As officer motivation was one primary aim of the program, one might have expected an increase in the number of arrests. However, as mentioned above, the Washington Metropolitan area was significantly affected by the 9/11 and the sniper tragedies. Both events required a great deal of effort and overtime from all police departments in the area. Without further data, it is difficult to draw any conclusions about the success of Extra Eyes on county arrests.