Literature Review
Ⅰ. HOTSPOT MAPPING
Hotspot can be defined as aggregations of raw crime data that identify geographic locations of highest incident concentration (Ratcliffe and McCullagh, 1999; Chainey and Ratcliffe, 2005). Hotspots have been formally recognized in the literature as early as 1751 when Henry Fielding suggested focusing on areas of high crime to deter offenders. A notable example of policing with hotspot is the study by Sherman et al., (1989), which found that over 50.4% of all calls to the Minneapolis police service came from only 3.3% of all places (p. 38). Unlike most crime-specific prevention techniques, hotspot methodology combined with intelligence policing can be used to prevent a range of crimes (Farrell and Sousa, …show more content…
Studies indicate that hotspot mapping prediction abilities differ between the different techniques and differ by crime type (Chainey et al., 2008). Spatial and Temporal Analysis of Crime (STAC) is one of the first hotspot mapping techniques (Illinois Criminal Justice Information Authority, 1996). It identifies the areas with the highest density and then fits a standard deviational ellipse to it. There has been criticism on STAC methodology due to its output as an ellipse and the parameter selection (Bowers & Hirschfield, 1999; Craglia, Haining, & Wiles, 2000; Ratcliffe, 2002b). Despite this, the method has been used by numerous police departments across the country for its ability to detect specific hotspot. Choropleth mapping or thematic mapping of geographic boundary areas, commonly census blocks or administrative districts, is a technique which is easy to execute and requires little technical knowledge to identify the areas with high crime intensity. But, the varying sizes and shapes of these areas make it difficult to identify hotspots based on the thematic shading and thus can be misleading (Eck et al., 2005; GIS and Crime mapping p.150, …show more content…
Here the problem is that one address is being targeted repeatedly (Polvi et al., 1991; Johnson et al., 1997; Pease, 1998; Sherman et al., 1989). Thinking from the perspective of an offender Pease (1998) noted that rather than searching for a new target and its location, it is easy to repeat the crime with the same target and near locations.There were different approaches for studying repeat victimization, while Groff and LaVigne (2002) and Gorr Olligschlaeger (2002) is considered as an area-based notion, Bowers et al., (2004) takes it as event-based i.e crime event focused. Research on repeat victimization shows that it is communicable within short distance and time after the original event (Bowers and Johnson, 2004; Johnson and Bowers, 2004a) taking the example of burglary for the year of 1997 for the county of Merseyside, UK. They show that crime is communicable within 400m and has an elevated risk for up to two months after the incident. Repeat victimization can be used to predict future hotspots of crime (Bowers et al., 2004; Farrell and Pease, 2001; Pease, 1998). Near repeat victimization occurs when counter measures are taken to prevent repeat victimization. For example, a burglary in a wealthy area can force the householder to up the security making it difficult for repeat victimization, hence the offender may prefer committing the crime at a neighboring house in the same area. Studies show that
Ⅰ. HOTSPOT MAPPING
Hotspot can be defined as aggregations of raw crime data that identify geographic locations of highest incident concentration (Ratcliffe and McCullagh, 1999; Chainey and Ratcliffe, 2005). Hotspots have been formally recognized in the literature as early as 1751 when Henry Fielding suggested focusing on areas of high crime to deter offenders. A notable example of policing with hotspot is the study by Sherman et al., (1989), which found that over 50.4% of all calls to the Minneapolis police service came from only 3.3% of all places (p. 38). Unlike most crime-specific prevention techniques, hotspot methodology combined with intelligence policing can be used to prevent a range of crimes (Farrell and Sousa, …show more content…
Studies indicate that hotspot mapping prediction abilities differ between the different techniques and differ by crime type (Chainey et al., 2008). Spatial and Temporal Analysis of Crime (STAC) is one of the first hotspot mapping techniques (Illinois Criminal Justice Information Authority, 1996). It identifies the areas with the highest density and then fits a standard deviational ellipse to it. There has been criticism on STAC methodology due to its output as an ellipse and the parameter selection (Bowers & Hirschfield, 1999; Craglia, Haining, & Wiles, 2000; Ratcliffe, 2002b). Despite this, the method has been used by numerous police departments across the country for its ability to detect specific hotspot. Choropleth mapping or thematic mapping of geographic boundary areas, commonly census blocks or administrative districts, is a technique which is easy to execute and requires little technical knowledge to identify the areas with high crime intensity. But, the varying sizes and shapes of these areas make it difficult to identify hotspots based on the thematic shading and thus can be misleading (Eck et al., 2005; GIS and Crime mapping p.150, …show more content…
Here the problem is that one address is being targeted repeatedly (Polvi et al., 1991; Johnson et al., 1997; Pease, 1998; Sherman et al., 1989). Thinking from the perspective of an offender Pease (1998) noted that rather than searching for a new target and its location, it is easy to repeat the crime with the same target and near locations.There were different approaches for studying repeat victimization, while Groff and LaVigne (2002) and Gorr Olligschlaeger (2002) is considered as an area-based notion, Bowers et al., (2004) takes it as event-based i.e crime event focused. Research on repeat victimization shows that it is communicable within short distance and time after the original event (Bowers and Johnson, 2004; Johnson and Bowers, 2004a) taking the example of burglary for the year of 1997 for the county of Merseyside, UK. They show that crime is communicable within 400m and has an elevated risk for up to two months after the incident. Repeat victimization can be used to predict future hotspots of crime (Bowers et al., 2004; Farrell and Pease, 2001; Pease, 1998). Near repeat victimization occurs when counter measures are taken to prevent repeat victimization. For example, a burglary in a wealthy area can force the householder to up the security making it difficult for repeat victimization, hence the offender may prefer committing the crime at a neighboring house in the same area. Studies show that