Sherman and Rogan (1995) found that the Kansas City (MO) Gun Experiment appeared to have a significant effect on gun seizures. The hot spots patrol officers found 29 guns in addition to the 47 guns seized in the target area by other police officers during phase 1, increasing the total guns found in the beat by 65 percent over the previous 6 months and almost tripling the number of guns found in car checks. Overall, there was an increase from 46 guns seized in the target area (beat 144) in the first 6 months of 1992 to 76 seized in the last 6 months. In the comparison beat (beat 242), there was no real change in the number of guns seized during the first 6 months of 1992, compared with the last 6 months of the year.
Looking at the 6-month rates of guns seized per 1,000 residents in the target and the comparison beat, there were 9.9 guns seized in the target area before patrols and 16.8 guns seized during patrols. In the comparison area, there were 10.4 guns seized before patrols and 8.8 guns seized during patrols.
Trends in Gun Crimes
There were 169 gun crimes in the target beat in the 29 weeks before the start of the hot spots patrols, but only 86 gun crimes in the 29 weeks during the phase 1 patrols. This is a 49 percent decline, with 83 fewer gun crimes. This change was statistically significant, using two different models of analysis (t–tests and ARIMA). In the comparison beat, there was a slight increase in gun crimes, from 184 in the 29 weeks before the hot spots patrols to 192 in the 29 weeks during the patrols. However, this change was not statistically significant.
Although gun crime dropped in beat 144, none of the seven neighboring beats observed any significant increase in gun crime. There was some evidence to suggest that the program’s benefits were diffused to two of the adjoining beats. Analyses using the ARIMA model showed significant reductions in gun crimes in beats 141 and 143.
Analysis showed that drive-by shootings declined during the 6-month period when hot spots patrols were active, compared with the periods without patrols, though the difference was not statistically significant. The comparison beat also showed no such difference, and there were no significant differences in the beats surrounding the targeted area.
Homicides were significantly lower in the targeted area during the 6-month program period than in the time period when the patrols were not active. There were no significant differences in homicides across those time periods in the comparison beat or in any of the contiguous beats.
There were no significant changes in the target or the comparison area on total calls for police services; calls about violence, property, or disorder crimes; total offense reports; or prior or violent offenses. The target area hot spot patrols concentrated primarily on guns, and it appears their effects were limited to gun crimes.
Sherman and Rogan (1995) used a quasi-experimental design to study the effectiveness of the Kansas City (MO) Gun Experiment. The target area, beat 144 (described above in Program Description) had high rates of violent crime, including drive-by shootings and homicides. The comparison area, patrol beat 242 in the Metro Patrol District, was selected because of the almost-identical number of drive-by shootings. The target area had a population of 4,528 persons, who were 53 percent female, were 92 percent nonwhite, and had a median age of 32 years. The comparison area had a population of 8,142 persons, who were 56 percent female, were 85 percent nonwhite, and had a median age of 31 years. The comparison area was slightly different from the target area. Aside from the higher population, the comparison area had three times the land area and had slightly higher housing prices.
Extra patrol attention on gun crime “hot spots” was provided by the Kansas City Police Department from July 7, 1992, through Jan. 27, 1993. The hot spots locations were identified by computer analysis of all gun crimes in the area. Gun crime was defined as any offense report in which the use of a gun by the offender is mentioned. Officers in the target area worked a total of 200 nights, 4,512 officer-hours, and 2,256 patrol car-hours. In the comparison area, no special efforts were made to limit police activities, but there were no funds available for extra patrol time.
The primary measures of interest were police activity and crime. The extra patrol hours were federally funded; therefore, separate booking was required to document the time. In addition, evaluators accompanied the officers on 300 hours of hot spots patrol and coded every shift activity narrative for patrol time and enforcement inside and outside of the area. Property room data on guns seized, crime reports, data on calls for service, and arrest records were all analyzed for the target and comparison area. Gun crimes were counted according to offense records showing that a gun had been used in the crime.
The data was analyzed using four different models. The primary analyses assumed that the gun crime counts were independently sampled from the beats examined before and after the intervention. This model treated the before–during different in the mean weekly rates of gun crime as an estimate of the magnitude of the effect of the hot spots patrols, and assessed the statistical significance of the differences with the standard two-tailed t–tests. A second model assumed that the weekly gun crime data points were not independent but were correlated serially, and thus required a Box–Jenkins ARIM (autoregressive integrated moving average) test of the effect of an abrupt intervention in a time series. A third model examined rate events (homicide and drive-by shootings) aggregated in 6-month totals on the assumption that those counts were independent, using one-way analysis of variance (ANOVA) tests. A fourth model also assumed independence of observations, and compared the target with the control beat in a before–during chi-square test.
The t–tests compared weekly gun crimes for all 29 weeks of the phase 1 patrol program (July, 7, 1992, through Jan. 25, 1993) with the 29 weeks preceding phase 1, using difference-of-means tests. The ARIM models extended the weekly counts to a full 52 weeks before and after the beginning of phase 1. The ANOVA model added another year before phase 1 (all of 1991) as well as 1993, the year after phase 1.
Following are CrimeSolutions.gov-rated practices that are related to this program:Hot Spots Policing
Used by many U.S. police departments, hot spots policing strategies focus on small geographic areas or places, usually in urban settings, where crime is concentrated. The practice is rated Effective. The analysis suggests that hot spots policing efforts that rely on problem-oriented policing strategies generate larger crime reduction effects than those that apply traditional policing strategies in crime hot spots.Evidence Ratings for Outcomes:
Reducing Gun Violence
| ||Crime & Delinquency - Multiple crime/offense types|
Reducing gun violence is a persistent public policy concern for communities, policymakers and leaders. To reduce gun violence, several strategies have been deployed including public health approaches (e.g., training and safe gun storage); gun buy-back programs; gun laws; and law enforcement strategies. The practice is rated Promising for reducing violent gun offenses.Evidence Ratings for Outcomes:
| ||Crime & Delinquency - Violent offenses|