Journal of Quantitative Criminology

, Volume 15, Issue 4, pp 451–493 | Cite as

Diffusion in Homicide: Exploring a General Method for Detecting Spatial Diffusion Processes

  • Jacqueline Cohen
  • George Tita
Article

Abstract

This article proposes a new method for examining dynamic changes in thespatial distribution of a phenomenon. Recently introduced exploratoryspatial data analysis (ESDA) techniques provide social scientists with anew set of tools for distinguishing between random and nonrandom spatialpatterns of events (Anselin, 1998). Existing ESDA measures, however, arestatic and do not permit comparisons of distributions of events in the samespace but across different time periods. One ESDA method—the Moranscatterplot—has special heuristic value because it visually displayslocal spatial relationships between each spatial unit and its neighbors. Weextend this static cross-sectional view of the spatial distribution ofevents to consider dynamic features of changes over time in spatialdependencies. The method distinguishes between contagious diffusion betweenadjoining units and hierarchical diffusion that spreads broadly throughcommonly shared influences. We apply the method to homicide data, lookingfor evidence of spatial diffusion of youth-gang homicides acrossneighborhoods in a city. Contagious diffusion between neighboring censustracts is evident only during the year of peak growth in total homicides,when high local rates of youth-gang homicides are followed by significantincreases in neighboring youth- nongang rates. This pattern is consistentwith a spread of homicides from gang youth to nongang youth. Otherwise, theincreases in both youth-gang and youth- nongang homicides generally occursimultaneously in nonneighboring tracts.

homicide exploratory spatial data analysis spatial diffusion contagious diffusion hierarchical diffusion 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

REFERENCES

  1. Anselin, L. (1988). Spatial Econometrics: Methods and Models, Kluwer Academic, Boston.Google Scholar
  2. Anselin, L. (1993). The Moran scatterplot as an ESDA tool to assess local instability in spatial association. Paper presented at GISDATA Specialist Meeting on GIS and Spatial Analysis, Amsterdam, December 1–5. West Virginia University, Regional Research Institute, Research Paper 9330.Google Scholar
  3. Anselin, L. (1995a). Local indicators of spatial association-LISA. Geograph. Anal. 27: 93–115.Google Scholar
  4. Anselin, L. (1995b). SpaceStat Version 1.80 Users Guide, Regional Research Institute, West Virginia University, Morgantown.Google Scholar
  5. Anselin, L. (1998). Interactive techniques and exploratory spatial data analysis. In Longley, P. A., Goodchild, M. F., Maguire, D. J., and Rhind, D. W. (eds.), Geographic Information Systems: Principles, Techniques, Management and Applications, John Wiley and Sons, New York.Google Scholar
  6. Block, R. (1998). Gang activity and overall levels of crime: A new method for defining areas of gang activity using police records. Paper presented at the Annual Meetings of American Society of Criminology.Google Scholar
  7. Block, C., and Block, R. (1993). Street gang crime in Chicago. Research in Brief, U.S. Department of Justice, National Institute of Justice, Washington, DC.Google Scholar
  8. Blumstein, A. (1995). Youth violence, guns, and the illicit drug industry. J. Crim. Law Criminol. 86: 10–36.Google Scholar
  9. Blumstein, A., and Cork, D. (1996). Linking gun availability to youth gun violence. Law Contemp. Problems 59(1): 5–24.Google Scholar
  10. Blumstein, A., and Rosenfeld, R. (1998). Explaining recent trends in U.S. homicide rates. J. Crim. Law Criminol. 88(4): 1175–1216.Google Scholar
  11. Canela-Cacho, J. A., Kenny, T., and Tyler, T. (1998). Gang Suppression in East Oakland: An Evaluation of the Oakland Police Department's 1996–97 Anti-Gang Initiative, Report Prepared for the Oakland Police Department. University of California-Berkeley, Berkeley.Google Scholar
  12. Clarke, R. V., and Weisburd, D. (1994). Diffusion of crime control benefits: Observations on the reverse of displacement. In Clarke, R. V. (ed.), Crime and Prevention Studies, Vol. 2, Criminal Justice Press, Monsey, NY.Google Scholar
  13. Cliff, A. D., Haggett, P., Ord, J. K., and Versey, G. R. (1981). Spatial Diffusion: An Historical Geography of Epidemics in an Island Community, Cambridge University Press, Cambridge.Google Scholar
  14. Cohen, J., and Tita, G. (1998). The gang-drug-gun nexus of homicide in Pittsburgh. Working paper. H. John Heinz III School of Public Policy and Management, Carnegie Mellon University, Pittsburgh, PA.Google Scholar
  15. Cohen, J., Cork, D., Engberg, J., and Tita, G. (1998). The role of drug markets and gangs in local homicide rates. Homicide Stud. 2(3): 241–262.Google Scholar
  16. Cork, D. (1996). Juvenile homicide and the availability of firearms. Working paper, H. John Heinz III School of Public Policy and Management, Carnegie Mellon University, Pittsburgh, PA.Google Scholar
  17. Cressie, N. A. C. (1993). Statistics for Spatial Data, rev. ed. John Wiley and Sons, New York.Google Scholar
  18. Curry, G. D., and Spergel, I. A. (1988). Gang homicide, delinquency, and community. Criminology 26(3): 381–405.Google Scholar
  19. Eck, J. E., and Weisburd, D. (1995). Crime places in crime theory. In Eck, J. E., and Weisburd, D. (eds.), Crime and Place (Vol. 4 in Crime Prevention Studies), Criminal Justice Press, Monsey, NY.Google Scholar
  20. Fagan, J., Zimring, F. E., and Kim, J. (1998). Declining homicide in New York City: A tale of two trends. J. Crim. Law Criminol. 88(4): 1277–1323.Google Scholar
  21. Fingerhut, L. A. (1993). Firearm mortality among children, youth, and young adults 1–34 years of age, trends and current status: United States, 1985–90. Advance Data 231, U.S. Department of Health and Human Services, National Center for Health Statistics, Hyattsville, MD.Google Scholar
  22. Fingerhut, L. A., Ingram, D., and Feldman, J. (1998). Homicide rates among U.S. teenagers and young adults: Differences by mechanism, level of urbanization, race and sex, 1987 through 1995. JAMA 280(5): 423–427.Google Scholar
  23. Haining, R. (1990). Spatial Data Analysis in the Social and Environmental Sciences, Cambridge University Press, Cambridge.Google Scholar
  24. Kellerman, A. (1996). Understanding and preventing violence: A public health perspective. National Institute of Justice Reviews, U.S. Government Printing Office, Washington, DC.Google Scholar
  25. Kennedy, D., and Braga, A. (1998). Homicide in Minneapolis: Research for problem solving. Homicide Stud. 2: 263–290.Google Scholar
  26. Kennedy, D., Braga, A., and Piehl, A. (1997). Mapping gangs and gang violence in Boston. In Weisburd, D., and McEwen, T. (eds.), Crime Mapping & Crime Prevention, Criminal Justice Press., Monsey, NY.Google Scholar
  27. Klein, M. (1995). The American Street Gang: Its Nature, Prevalence and Control, Oxford University Press, New York.Google Scholar
  28. Klein, M., Maxson, C., and Cunningham, L. (1991). Crack, street gangs, and violence. Criminology 29: 623–650.Google Scholar
  29. Lasley, J. (1998). Designing out gang homicides and street assaults. Research in Brief, U.S. Department of Justice, National Institute of Justice, Washington, DC.Google Scholar
  30. Maxson, C. (1998). Gang members on the move. OJJDP Juvenile Bulletin, U.S. Department of Justice, Office of Juvenile Justice and Delinquency Prevention, Washington, DC.Google Scholar
  31. Moore, J. (1991). Going Down to the Barrio: Homeboys and Homegirls in Change, Temple University Press, Philadelphia.Google Scholar
  32. Spergel, I., and Curry, D. (1990). Strategies and perceived agency effectiveness in dealing with the youth gang problem. In Huff, C. R. (ed.), Gangs in America: Diffusion, Diversity and Public Policy, Sage, Newbury Park, CA.Google Scholar
  33. Tita, G. (1999a). An Ecological Study of Violent Urban Gangs and Their Impact on Crime, Unpublished doctoral dissertation, Carnegie Mellon University, Pittsburgh, PA.Google Scholar
  34. Tita, G. E. (1999b). Mapping the set space of urban street gangs. In Hendrix, E. H., Dent, B., and Turnbull, L. S. (eds.), The Atlas of Crime, Oryx Press, Phoenix, AZ.Google Scholar
  35. Tita, G., Engberg, J., and Cohen, J. (1998). An ecological study of gangs: The social organization of 'set space.' Working paper, H. John Heinz III School of Public Policy and Management, Carnegie Mellon University, Pittsburgh, PA.Google Scholar

Copyright information

© Plenum Publishing Corporation 1999

Authors and Affiliations

  • Jacqueline Cohen
    • 1
  • George Tita
    • 2
  1. 1.School of Public Policy and ManagementCarnegie Mellon UniversityPittsburgh
  2. 2.The Rand CorporationSanta Monica

Personalised recommendations