Spatial Configuration of Places Related to Homicide Events in Washington, DC, 1990-2002 (ICPSR 4544)

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Study Purpose View help for Study Purpose

The purpose of this research was to further understanding of why crime occurs where it does by exploring the spatial etiology of homicides that occurred in Washington, DC, between 1990 and 2002. This research sought to fill a gap in the criminological literature by (1) disaggregating homicides by motive to provide a more exact analysis of movement for each particular type; (2) exploring the distances to homicide for victims and offenders; (3) describing the relationships between victims, offenders, and places through a comparison of two mobility triangle typologies; and (4) applying various cartographic methods for representing the interactions between victim, offender, and place.

Study Design View help for Study Design

The researchers accessed records from the case management system of the Metropolitan Police, District of Columbia (MPDC), Homicide Division to collect data regarding offenders and victims associated with homicide cases that occurred in Washington, DC, during the 13-year period 1990-2002. While most victims resided in Washington, DC, those who were killed in the city but had resided in the adjacent states of Maryland and Virginia were also included.

For each case, addresses of the incident location, the victim's residence, and offender's residence were geocoded using ArcGIS 8.3.

ArcView 3.x was used to calculate both Euclidean distance and shortest path distance along the streets between the home addresses of the victim and offender(s) for each case, and then between each home address and the homicide location.

The researchers applied the concept of triad as developed by Block et al. (2004) in order to create a unit of analysis for studying the convergence of victims and offenders in space. A triad is the combination of locations associated with each case: the homicide incident, the residence of the victim, and the residence(s) of the offender(s). Multiple triads are formed when multiple offenders are associated with a homicide. For example, three triads would be developed for an incident in which there are three offenders who killed a victim. The researchers believed it was important to include all known offenders because they have different mobility patterns.

The researchers categorized the triads according to their geometry. Dots represent homicides where the victim and offender lived in the residence where the homicide occurred. Lines represent homicides that occur in the home of either the victim or offender. Triangles consist of three non-coincident locations; that is, a victim and offender did not live together, and the homicide crime took place somewhere other than either the victim's or the offender's residence.

The researchers then classified each triad according to two separate mobility triangle classification schemes:

• Traditional Mobility, based on shared or disparate social areas, according to Normandeau's (1968) five-category typology. The five categories are Neighborhood Triangle, Offender Mobility Triangle, Victim Mobility Triangle, Offense Mobility Triangle, and Total Mobility Triangle.
• Distance Mobility, based on relative distance categories between locations. The categories are 0.25 miles, 0.50 miles, 0.75 miles, and 1 mile. Normandeau's (1968) five-category typology was then applied to each category.

Finally, the researchers classified each triad by the neighborhood associated with the location of the homicide incident, the location of the victim's residence, and the location of the offender's residence.

Sample View help for Sample

Data for this study were compiled from homicide case records of the Metropolitan Police, District of Columbia (MPDC), for the 13 year period 1990 through 2002.

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Universe View help for Universe

All homicide cases in Washington, DC, from 1990 to 2002.

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Description of Variables View help for Description of Variables

The Offender Characteristics Data (Dataset 1) contain 23 variables, comprised of 3 identification variables (case ID, victim ID, offender ID); 4 variables describing characteristics of the offender (age, age category, gender, race); 8 variables describing motive(s) for the homicide (argument, domestic violence, drug-related, gang-related, retaliation, robbery, other, unknown); 1 variable indicating the status of the case (open or closed); 1 variable describing the weapon used (firearm or other); 1 variable describing the offender-to-victim relationship (unknown, stranger, acquaintance, intimate); 4 variables describing the distance from the offender's home to the homicide location (Euclidian distance as well as street distance, in feet and in miles), and 1 distance category variable (offender home homicide, offender middle-distance, offender long-distance).

The Victim Characteristics Data (Dataset 2) contain 23 variables, comprised of 2 identification variables (case ID, victim ID); 1 variable describing the victim number in a particular homicide case; 2 variables describing when the case was ruled a homicide (month, year); 1 variable indicating the status of the case (open or closed); 4 variables describing characteristics of the victim (age, age category, gender, race); 8 variables describing motive(s) for the homicide (argument, domestic violence, drug-related, gang-related, retaliation, robbery, other, unknown); 1 variable describing the weapon used (firearm or other); and 4 variables describing the distance from the victim's home to the homicide location (Euclidian distance as well as street distance, in feet and in miles).

The Triads Data (Dataset 3) contain 39 variables, comprised of 4 identification variables (case ID, triad ID, offender ID, victim ID); 1 variable indicating the year the case was ruled a homicide; 4 variables describing characteristics of the victim (age, age category, race, gender); 4 variables describing characteristics of the offender (age, age category, race, gender); 7 variables describing motive(s) for the homicide (argument, domestic violence, drug-related, gang-related, retaliation, robbery, other); 1 variable indicating the status of the case (open or closed); 1 variable describing the weapon used (firearm or other); 6 variables describing distance: victim's home to home location, offender's home to homicide location, and offender's home to victim's home (Euclidian distances and street distances for each, each in miles); 1 variable describing the offender-to-victim relationship (stranger, acquaintance, intimate); 1 location code variable (inside, outside); 1 variable to describe the geometry associated with the triad relationship among offender, victim, and offense locations for each case (dot, line, triangle); 1 traditional mobility variable incorporating Normandeau's (1968) social area designation (neighborhood, offender, victim, offense, total); 4 distance mobility category variables, each incorporating Normandeau's (1968) social area designation (neighborhood, offender, victim, offense, total); and 3 variables for neighborhood cluster designations (for homicide location, victim residence location, and offender residence location).

The Geographic Information Systems (GIS) Data (Dataset 4) consist of 7 shapefiles.

• DCMDVAstreets.shp: US Census TIGER street centerlines for the District of Columbia, Maryland, and Virginia.
• DCNeighborhoodClusters.shp: Neighborhood clusters in the District of Columbia, redistributed with permission from opendata.dc.gov.
• DCStreeets.shp: Street centerlines for the District of Columbia, redistributed with permission from opendata.dc.gov.
• HomicideLoc_ClosedCasesOnly_NoAddresses.shp: Location points of homicide incidents for closed cases.
• OffendersLoc_ClosedCasesOnly.shp: Location points of offenders' residences for closed cases. (Note: contains no address data)
• Triads_ClosedCasesOnly_NoAddresses.shp: Location points of triads for closed cases.
• VictimsLoc_ClosedCasesOnly.shp: Location points of victims' residences for closed cases. (Note: contains no address data)

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Not applicable.

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None.

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Original Release Date View help for Original Release Date

2015-07-29

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None.

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