Punch the Alien to send E-mailOVERVIEW
This project is part of the MPA program at UTDallas for completion of a GIS certificate. The project consists of noting the location and concentration of concealed handgun permits that were issued in Texas in 1996 and observing if there was any impact on criminal activity as a result of a citizen's ability to carry a weapon for self-defense through the use of GIS. The use of GIS in designing thematic maps can be invaluable in a variety of settings such as business, government, marketing, science, etc. The ability of GIS to perform as an analytical tool is only as limited as ones imagination.
During research for a presentation on concealed handgun legislation in Texas I found a web page provided by the Concealed Handgun Unit (CHU) of the DPS. Their page contained concealed handgun permit distribution in the State of Texas by zip code. I downloaded this information into EXCEL and then an ACCESS database.
This project was designed using both ATLAS and ARCVIEW GIS applications. As an intern at a large retail organization I had access to an ATLAS GIS which allowed utilizing zip code and county files in agf and aiff spatial data form. I linked my ACCESS database of permits by zip code to ATLAS and the zip code files contained in this system. This, along with the county files, gave me a cloropleth map of Texas with the distribution of handgun permits by county.
With a program I downloaded from ESRI I converted the agf zip code and county files into ARCVIEW shapefiles and rebuilt the entire project using ARCVIEW at home for analysis and then distribution on the internet.
Metadata
The zip code and county boundary shape files were in decimal degrees with no projection. For this project I used the following properties in ARCVIEW:
The statistical data on criminal activity was obtained once again from the DPS. This data contains total crime broken down into categories (homicide, domestic violence, burglary, etc.) for the years 1995 and 1997. Unfortunately, the data could only be obtained for the counties in Texas instead of by zip code. As a result I averaged the number of permits for the zip codes in each county by the 1997 population. This entailed quite a bit of work because some of the zip code boundaries overlapped county boundaries so I obtained the areas for each zip code boundary that overlapped the county boundary and proportioned the number of permits in the zip code boundaries accordingly. Once again, the data was loaded in to ARCVIEW with ACCESS.
According to a definitive study performed on states with concealed handgun permits by Lott and Mustard(1996), the authors discovered some startling facts concerning a change in criminal behavior. The authors have shown that there was a substantial drop in violent crime and a corresponding increase in stealth crime as criminals strove to avoid citizens carrying concealed handguns in those states that had laws allowing it. With this in mind I combined all the violent crimes (murder, rape, robbery, aggravated assault) in each county and normalized the results with 95 and 97 populations and did the same for stealth crimes (burglary, theft, and motor vehicle theft). I then performed a % change calculation for the years 95 and 97 to see what change, if any, there had been in violent and stealth crime throughout the state of Texas. Of course this is all contingent on criminals having some sense of where these areas are. Perhaps the fact that the law in question had been passed in Texas at all made any area suspect. If so these patterns will be sought and hopefully revealed in the conclusion of this analysis.
Although this window for analysis is very narrow (only two years worth of data), any discernable trend might benefit some organizations such as the CHU and the Texas legislature that rely on such data to determine the effects of the implementation of this law.
CHANGE IN VIOLENT CRIME
As mentioned in the Project Description, the study by Lott and Mustard (1996) demonstrated that states that allowed its citizens to carry concealed handguns experienced a noticeable decline in violent crime with a concurrent increase in stealth crime. Maps 1 and 2 on the GIS Map page are an example of thematic maps depicting two variables. Map 1 demonstrates the correlation of distribution of concealed handgun permits to change in violent crime between 1995 and 1997. .
In analyzing changes in violent crime between 1995 and 1997 in the state of Texas it appears that most of the counties have either had a decrease in crime in areas where few permits were issued or a decrease in crime where a moderate number of permits were issued. Dallas and Tarrant Counties fall in the moderate # of permits issued/decrease in violent crime category. Bexar and Harris fall into the few permits issued/decrease in violent crime category. These counties were mentioned because they contain the largest metropolitan areas in Texas where the major portion of violent and stealth crimes are reported.
A few counties stand out and deserve special mention. Leon County fell into the moderate number of permits issued/increase in violent crime category. Briscoe fell in to the few permits issued/increase in violent crime category. A few counties, such as Bandera, Terrell, Llano, etc., fall into the many permits issued/decrease in crime category. There were no counties that fell into the many permits/increase category. The remainder of the counties belong to the moderate number of permits/no change group.
CHANGE IN STEALTH CRIME
Turning to Map 2 (Stealth Crime) it's apparent that the patterns look similar but the meaning is much different. The pattern of most of the counties in the state belonging to either of two categories still holds. One of the categories has changed to reflect change in stealth crime. In this map Dallas, Harris and Tarrant Counties exhibit an decrease in stealth crime after a moderate number of permits had been issued. Bexar and many other counties in the south and western portion of the state fall into the few permits issued/decrease in stealth crime category. Only Kent and Hartley belong to the few permits/increase in stealth crime category while Kenedy County stands alone in the moderate number permits issued/increase in stealth crime category.
The results of this project are mixed at best. The correlation between the distribution of concealed handguns and the % change in violent crime is obvious. The majority of counties in the state show a decrease in violent crime between 1995 and 1997 with only a few rare exceptions. This appears to validate Lott and Mustard's study that once a state allows its citizenry to carry concealed handguns criminals feel the need to tread more cautiously. Most of the other citizens approach each other more carefully as well, no doubt. Tempers will probably flair less when one considers the consequences.
The decrease or no appreciable change in stealth crime was almost universal within the State of Texas. This is in direct conflict with the study of Lott and Mustard. Perhaps the law officials in the State of Texas have developed a way to contain stealth crime in the face of a decrease in violent crime brought about by criminals fear of discovery by someone carrying a handgun. If so my hat is off to them.
Another note must be made of the decrease in violent crime. It may well be that the new concealed handgun permits in the State of Texas had nothing to do with the decrease in violent crime. There are so many factors involved in criminal activities and crime prevention that to attribute such a large scale result to this law may be wishful thinking. An important point to remember is that the data should include many years of the law being in effect and only 1997 was available for concealed handguns in the State of Texas after the legislation was passed into law. Be that as it may I believe the concept to be valid in terms of following Lott and Mustard's study. I would like to see this project repeated in about 7 years when more data would make the results quite reliable. It would also help a great deal if crime data were available by zip code instead of by county. I imagine this would be of immense interest to people who live in these zip codes. It might even be used to determine where people would choose to live.
GRATITUDE
I would like to thank the following people without whom this project would not exist:
Dr. Ron Briggs--a GIS God and my project mentor. While he did not invent GIS he probably would have if no one else had.
Jeff Wooten--my immediate supervisor for my internship with the patience of a saint.
Mark Kalmbacher--the project manager who hired me for my internship and who shares a better world with me through Middle Earth.
Pam Nickel--DPS information specialist who provided the critical crime data.
I ask forgiveness for anyone's name I left out because I know there were more.
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