The Relationship Between Part I Crimes and Public High School Proximity. A study by Mike B. Ahn

Project Focus OBJECTIVE: to see if there is a statistically higher incidence of Part I Crimes near public high schools in Arlington, Texas. PART I CRIMES ARE… Murder, Rape, Assault (Aggravated), Robbery, Burglary, Theft, Motor Vehicle Theft, and Arson. SUBOBJECTIVE: if a statistical significance is observed, then strength of the discovered relationship will be compared with other traditional crime influencing spatial factors (e.g. race, low income, etc.).

Prior Studies… Previous research proved that there is a relationship between nearness to public high schools and higher instances of Part I crimes. In San Diego, California it was found that residential areas that were adjacent to public high schools had more crime than areas that were more than one city block away from these schools (Roncek and LoBosco, 1983). In Cleveland, Ohio to be next to a public high school meant that there was an additional five Part I crimes per city block annually compared to the rest of the city (Roncek and Faggiani, 1985).

DATA NCTCOG: 2000 census blocks of Arlington, Texas. The City of Arlington Police Department: Point shapefile of all crime reports from June 1, 2006 to May 31, 2007. GPS: Public high school points.

METHODS PREPARATION Locate School Blocks with GPS. Had to edit Arlington data, filter out non-Part I crimes, and consolidate crimes that were a sub-category of Part I crimes. Make comparable layers: School blocks, Adjacent Blocks, and City Blocks. Had to delete Ft. Worth. Hawths Tools to count points per polygon

METHODS T-test average number of each Part I crime on school blocks with the average number of Part I crimes on the adjacent blocks. ^If no difference, combine the blocks. T-test the average number of each Part I crime on combined blocks with the average number of Part I crimes on the rest of the city blocks. Run t-test for secondary adjacent blocks and all other outside blocks.

…METHODS continued… REGRESSION ANALYSIS: (using GeoDa) for each Part I crime category to confirm t-test results. SUBOBJECTIVE: If close proximity of a public high school has an increasing effect on number of crimes; then regression analysis will be ran on other crime influencing factors in Arlington so that regression strength of school proximity can be compared.

Problems Encountered Finding data. Crime data did not line up with census data. Block data was scarce. Bad Communication: it might not be a user/technical issue but it was a project issue. A few types of Part I crimes had disruptive spatial bias (construction burglaries, bank robberies, etc.), so they were removed from the study. Could not create an address locator. … I could’ve included the encased secondary blocks but I took a look at their crime numbers and they didn’t deviate much from the mean so for that and just to keep the methods free from any kind of unruly bias I stayed true to the rules.

PROGRESS Roughly ½ way to completion. Research, Preparation, and Communication was half the battle. Enough t-tests have been performed to foreshadow likely final results.

Mean on Adjacent Blocks COMPARING THE AVERAGE NUMBER OF CRIMES ON BLOCKS CONTAINING SCHOOLS WITH THE AVERAGE ON ADJACENT BLOCKS   Mean on School Blocks Mean on Adjacent Blocks t-statistic Murder not significant Rape 0.333 0.172 0.478 Assault 3.167 2.184 0.635 Robbery 0.368 0.105 Burglary 8.500 5.149 0.896 Theft 3.667 3.172 0.27 Auto Theft 2.000 0.782 0.887 Arson df t-critical 6 Blocks 87 Blocks 91 1.66 @ 95% CI t-statistic > t-critical for significant difference* No statistical significant difference, so blocks containing high schools was combined with adjacent blocks to compare with the remainder of the city blocks.

COMPARING THE AVERAGE NUMBER OF CRIMES WITHIN 1 BLOCK OF SCHOOL PROXIMITY WITH THE AVERAGE ON ALL OTHER BLOCKS   Mean Near School Proximity Mean On All Other Blocks t-statistic Murder <0.01 not significant* Rape 0.183 0.104 1.787 significant Assault 2.247 1.284 2.702 Robbery 0.366 0.176 2.33 Burglary 5.366 2.641 2.947 Theft 3.204 1.691 3.143 Auto Theft 0.860 0.523 2.001 Arson df t-critical 92 Blocks 3473 Blocks 3565 1.645 @ 95% CI

PRESENT SUMMARY OF RESULTS The current extent study seems to show that there is a definite relationship between close proximity to public high schools and higher incidences of crime. All relevant categories of Part I crime have higher incidence near schools. (except arson, murder) At this point the results are doing better than prior studies done on the cities of Cleveland and San Diego. (more clean cut.)

Work that still remains… Examine the range of the proximity effect: t-test the secondary adjacent blocks with all other blocks (tertiary blocks if necessary)… Complement current results with REGRESSION ANALYSIS. Compare the significance of this crime indicator with other types of indicators (e.g. population density, single residents, income, etc.)

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