Data Driven Policing:Data Driven Policing:

Homicide Concentration and Homicide Concentration and Distribution Patterns in LondonDistribution Patterns in London

Detective Superintendent Mark Jackson&

Barak Ariel, PhD

All Homicide Offences (1st Apr 00 to 31st Mar 10)

• Is Homicide a random event in time?

• Is Homicide a random event in space?

• What are the possible links between homicide locations, offenders, victims and other factors, at the micro-place level?

Research Questions?

The stability of crime trends at places over time suggests a “strong coupling” of crime to place

David Weisburd, Cody W. Telep, Anthony A. Braga (2010). The Importance of Place in Policing: Empirical Evidence and Policy Recommendations. Bra Publications

Place-Based Criminology

• 74% of serious gun crime assault was committed in 5% of street and intersections

(Braga et al 2010)

• 5% of addresses/intersections produce 100% of the calls for predatory crimes, i.e. robbery

(Sherman et al 1989)

• 3.5% of addresses account for 50% of crime calls (Sherman et al 1987)

(some of the) Research Evidence:

London Metropolitan Police Data:

• 10 year period from (1.4.2000 - 31.3.2010) within the Metropolitan Police area of London

• Homicide Locations = 1,664 (98.2% geo-coded)

• Victims Locations = 1,714 (87.3% geo-coded)

• Offenders Location = 2,382 (84.3% geo-coded)

• Socioeconomic Deprivation Measures for 4,760 LSOAs

Temporal Patterns

London Homicides (2000-2010) by Year (n=1,714)

London Homicides (2000-2010) by Month (n=1,664)

London Homicides (2000-2010) by Day of Week (n=1,664)

London Homicides (2000-2010) by Hour of Day (n=1,664)

Spatial Patterns

Homicide Offence locations by Borough

Offences by borough

100 to 125 (1)75 to 99 (5)50 to 74 (10)25 to 49 (10)1 to 24 (6)0 (1)

Homicide Offence locations by Ward

Offences by wards

16 (1)12 to 15 (3)9 to 12 (15)6 to 9 (63)3 to 6 (182)1 to 3 (233)0 (127)

Homicide Offence locations by LSOA

Or put it another way

Zero Homicides (1st Apr 00 to 31st Mar 10)

Homicide Offence locations in Westminster Wards

West End

St James

All Domestic Violence Homicides (1.4.00 to 31.3.10)

All Gun-Related Homicides (1.4.2000 to 31.3.2010)

All Knife-Related Homicides (1.4.2000 to 31.3.2010)

Connecting Homicide Places to People

at LSOA level

LSOA Characteristics

Greater

Metropolitan

City

LSOA

Homicide

Locations

LSOA

Victim

Locations

LSOA

Offender

Locations

N 4,760 1,240 1,202 1,386

Population size 7.1-7.4M 1,634 1,496 2,030

Mean N of persons 1,505-1,626 1,660 1,645 1,585

Area (Hectares) 32.9 31.4 27.4 39.4

Density rate per Hectare 84.1-90.8 93.4-101.7 97.7-105.9 69.2-73.1

• 72% of London's LSOAs (n=3,414) did not have a resident accused of homicide

Homicide Offenders

• 75.5% (n=3,597) of LSOAs did not have a resident victim of homicide

Homicide Victims

• 6% of LSOAs contributed 42% of homicides over 10 year period

Concentrations of Homicide

• 9% of LSOAs contributed 53% of homicide offenders over 10 year period

Concentrations of Offenders

• 5% of LSOAs contributed 35% of homicide victims over 10 year period

Concentrations of Victims

Deprivation Levels at LSOA

• There are predictable “hot times” of homicide

• The stability of homicide trends at places over time suggests a “strong coupling” of:

1. Homicides to place (6% 42%)

2. Homicide offenders to place (9% 53%)

3. Homicide victims to place (5% 35%)

Summary 1

• 2% of homicide offenders kill within their LSOA

• 60% of victims are killed within their LSOA

• Medium-size relationship between overall crime patterns & deprivation levels with: 1. Homicide LSOA (ES = 0.5)

2. Homicide victims LSOA (ES = 0.5)

• Small but negative relationship between overall crime patterns & deprivation levels with: Homicide offenders (ES = -0.14)

Summary 2

Data Driven Policing:Data Driven Policing:

Homicide Concentration and Homicide Concentration and Distribution Patterns in LondonDistribution Patterns in London

Detective Superintendent Mark Jackson&

Barak Ariel, PhD