dynamic social network analysis of al-qaeda

Dynamic Social Network Analysis of Al-Qaeda

CDT Matthew R Webb

1 November 2006

ARL/USMA Technical Symposium

Agenda

• What is Dynamic Social Network Analysis?– Network Measures– Statistical Process Control

• Application: Al-Qaeda– Method– Preliminary Results

• Future Research• Questions

What is Dynamic Network Analysis?

• Social Network Analysis (SNA) is the mathematical methodology of quantifying connections between individuals and groups.

• Dynamic SNA compares snapshots of a network over time to determine when the network changes.

TimeTime

ExperienceExperience

Network Measures

• Key Network Measures– Density– Degree Centrality– Closeness Centrality– Betweeness Centrality– Diameter

Graph courtesy of Steve Borgatti

Statistical Process Control

• Calculates a statistic from sequential measurements of a random process and compares it to a control limit.

• Used extensively in quality engineering.– Example cutting boards at a lumber mill

Statistical Process Control

• Cumulative-Sum Control Chart– Good at detecting small changes in mean over time– Built in change point detection

• Calculate Zi value for each time-period.

• Two Charts (To Detect Increase and Decrease)

/0 ii xZ

},0max{ 1

ttt CkZC

},0max{ 1

ttt CkZC

Application - Method

• The Office of Naval Research maintains network data on Al-Qaeda.

• Ran CUSUM Control Chart for three Network Measures (Betweeness, Closeness, and Density)

0

0.002

0.004

0.006

0.008

0.01

0.012

1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004

Time

Betweeness

Density

Closeness

Closeness CUSUM Chart for Al-Qaeda (1994-2004)

0

1

2

3

4

5

6

7

8

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004

C+

Application - Results

Signal

Change Point

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004Closeness 0.0027 0.003 0.0028 0.0028 0.0031 0.003 0.0032 0.0034 0.0024 0.0015 0.0004Z -0.8729 1.0911 -0.2182 -0.2182 1.7457 1.0911 2.4004 3.7097 -2.8368 -8.7287 -15.9299C+ 0 0.5911 0 0 1.2457 1.8368 3.7372 6.9469 3.6101 0 0C- 0.3729 0 0 0 0 0 0 0 2.3368 10.5655 25.9955

Signal 0 0 0 0 0 0 0 1

The control chart signals a change in the network in 2000/2001.

A MLE of the change point is 1997. - Increased activity of IG - Bright Star ’97 cut short - Feb ’98 Islamic Front - Embassy bombings in ’981997 was THE critical planning year for Al-Qaeda.

Future Research

• New Data– IkeNet and TOEP Data

• Near-Complete Network Picture• More Snapshots

• New Approaches– What if Network Picture is Incomplete?– What Network Measures are the most telling?– Which Control Chart work best?

Questions?