1. welcome introduction-handout - papachristos · sna workshop ~ yale university 11-12 august 2015...

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SNA Workshop ~ Yale University 11-12 August 2015 A.V. Papachristos 1 Yale University SOCIAL NETWORK ANALYSIS FOR CRIMINAL J USTICE & 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

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Page 1: 1. Welcome Introduction-Handout - Papachristos · SNA Workshop ~ Yale University 11-12 August 2015 A.V. Papachristos 3 SNA Workshop ~ 2015 ‣ The spread of disease, fashion, information,

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

Page 2: 1. Welcome Introduction-Handout - Papachristos · SNA Workshop ~ Yale University 11-12 August 2015 A.V. Papachristos 3 SNA Workshop ~ 2015 ‣ The spread of disease, fashion, information,

SNA Workshop ~ Yale University 11-12 August 2015

A.V. Papachristos 2

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

Page 3: 1. Welcome Introduction-Handout - Papachristos · SNA Workshop ~ Yale University 11-12 August 2015 A.V. Papachristos 3 SNA Workshop ~ 2015 ‣ The spread of disease, fashion, information,

SNA Workshop ~ Yale University 11-12 August 2015

A.V. Papachristos 3

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

Page 4: 1. Welcome Introduction-Handout - Papachristos · SNA Workshop ~ Yale University 11-12 August 2015 A.V. Papachristos 3 SNA Workshop ~ 2015 ‣ The spread of disease, fashion, information,

SNA Workshop ~ Yale University 11-12 August 2015

A.V. Papachristos 4

Bearman, Moody, & Stovel 2004

What is a Social Network?

A FINITE SET (OR SETS) OF ACTORS AND THE RELATION

(OR RELATIONS) DEFINED ON THEM

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A.V. Papachristos 5

2 Ties

1 Nodes

SNA Workshop ~ 2015

Edges

relations ties arcs

arrows

Nodes

actors dots

vertices

Examples

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SNA Workshop ~ Yale University 11-12 August 2015

A.V. Papachristos 6

A Student Group

A Classroom

Page 7: 1. Welcome Introduction-Handout - Papachristos · SNA Workshop ~ Yale University 11-12 August 2015 A.V. Papachristos 3 SNA Workshop ~ 2015 ‣ The spread of disease, fashion, information,

SNA Workshop ~ Yale University 11-12 August 2015

A.V. Papachristos 7

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

Page 8: 1. Welcome Introduction-Handout - Papachristos · SNA Workshop ~ Yale University 11-12 August 2015 A.V. Papachristos 3 SNA Workshop ~ 2015 ‣ The spread of disease, fashion, information,

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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?

Page 9: 1. Welcome Introduction-Handout - Papachristos · SNA Workshop ~ Yale University 11-12 August 2015 A.V. Papachristos 3 SNA Workshop ~ 2015 ‣ The spread of disease, fashion, information,

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A.V. Papachristos 9

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

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A.V. Papachristos 10

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

Page 12: 1. Welcome Introduction-Handout - Papachristos · SNA Workshop ~ Yale University 11-12 August 2015 A.V. Papachristos 3 SNA Workshop ~ 2015 ‣ The spread of disease, fashion, information,

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New Haven, CT

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A.V. Papachristos 13

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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

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6 %

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6 %

85 %

Newark, NJ

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Newark, NJ

Newark, NJ

6% 65%

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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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A.V. Papachristos 20

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