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SNA Workshop ~ Yale University 11-12 August 2015
A.V. Papachristos 1
Yale University
SOCIAL NETWORK ANALYSIS FOR CRIMINAL JUSTICE & VIOLENCE PREVENTION PRACTITIONERS
Yale Institute for Network Science 11-12 August 2015
Andrew V. Papachristos, Ph.D.
July 29th - 30th Yale Law School
Day 1
SNA Workshop ~ 2015
Learning Objectives
(1) Familiarize you with possibilities of SNA
(2) Expose you to different types of SNA data
(3) Get hands dirty with software and data
SNA Workshop ~ 2015
Roadmap ~ Day 1
(1) What is Social Network Analysis?
(2) Real World Examples of Applied SNA
(3) Introduction to Network Data
(4) Introduction to Network Software 1: RStudio
SNA Workshop ~ Yale University 11-12 August 2015
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Section 1. What is Social Network Analysis?
SNA Workshop ~ 2015
‣ It’s a Small World
‣ Six Degrees of . . .
‣ It’s not what you know, but . . .
‣ The “good old boys” club
‣ The Strength of Weak Ties
‣ Bowling Alone
SNA Workshop ~ Yale University 11-12 August 2015
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SNA Workshop ~ 2015
‣ The spread of disease, fashion, information, technology, and capital
‣ Political & Social Influence
‣ Attitudes, Opinions, & Behaviors
‣ Physical & Social Influence
‣ Friendships, Marriages, Relationships
‣ Human & Animal Societies
What predicts the risk of getting an STD?
Bearman, Moody, & Stovel 2004
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Bearman, Moody, & Stovel 2004
What is a Social Network?
A FINITE SET (OR SETS) OF ACTORS AND THE RELATION
(OR RELATIONS) DEFINED ON THEM
SNA Workshop ~ Yale University 11-12 August 2015
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2 Ties
1 Nodes
SNA Workshop ~ 2015
Edges
relations ties arcs
arrows
Nodes
actors dots
vertices
Examples
SNA Workshop ~ Yale University 11-12 August 2015
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A Student Group
A Classroom
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What is Social Network Analysis?
Social Network Analysis is the study of social relations and their influence on individual, group, and system behavior
Looking for Social Structure ~ regularities in patterns among units
1
2
SNA Workshop ~ 2015
Networks as: Dependent Variables
SNA Workshop ~ Yale University 11-12 August 2015
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SNA Workshop ~ 2015
Networks as: Independent Variables
Criminal Justice Applications & Uses
SNA Workshop ~ 2015
The Study/Investigation of Criminal Groups 1
‣ How Cohesive are particular groups?
‣ What does a group’s structure look like?
‣ Who are important players?
SNA Workshop ~ Yale University 11-12 August 2015
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SNA Workshop ~ 2015
SNA to study social contexts 2
‣ Peer influence on crime/delinquency
‣ “Landscape” of violence
‣ Social Control (or lack thereof)
SNA Workshop ~ 2015
Networks as conduit for diffusion 3
‣ Drugs
‣ Money
‣ Violence
‣ Information
‣ Guns
Gun Violence
SNA Workshop ~ Yale University 11-12 August 2015
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Why guns?
• Violence tends to occur between people who know each other
• Gun violence is more concentrated within populations/places
• Gun use is associated with peer influence
• Guns are durable goods
Applications
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(1) Mapping Conflicts & Violence
Group Audits
Chicago, IL
SNA Workshop ~ Yale University 11-12 August 2015
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New Haven, CT
SNA Workshop ~ Yale University 11-12 August 2015
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(2) Identifying Group Structures
Boss
Underboss Underboss
St. Lt St. Lt St. LtSt. Lt
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SNA Workshop ~ 2015
7-2 Gangster Disciples (Chicago, IL)
(3) Who’s At Risk of Being a Gunshot Victim?
Boston, MA
SNA Workshop ~ Yale University 11-12 August 2015
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6 %
SNA Workshop ~ Yale University 11-12 August 2015
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6 %
85 %
Newark, NJ
SNA Workshop ~ Yale University 11-12 August 2015
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Newark, NJ
Newark, NJ
6% 65%
SNA Workshop ~ Yale University 11-12 August 2015
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Chicago, IL
@AVPapachristosPapachristos, Wildeman, & Roberto 2015
• 6 % of total population
• 40 % of arrested population
• 70 % of all shootings
• 89% in a single network
Papachristos, Wildeman, & Roberto 2014
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62.14
345.62
740.48
0
200
400
600
800
City Rate At Least 1 Arrest Arrest In Network
Non-Fatal Shooting Rate (per 100,000)
Associate
Shooting Victim
Co-Offending Tie
Family Tie
4 0 % O F A S S O C I A T E S A R E
V I C T I M S
T e x t