Transcript Social Network Analysis - British Computer Society

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Social Network Analysis
Mark Round
+44 (0) 1684 89 4450
[email protected]
Date: 04 Dec 2007
Location: BCS North London Branch
www.QinetiQ.com
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‘Social
Networks’
xkcd.com
SNA Overview 2
reproduced with permission from John Robb,
GlobalGuerillas.com
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SNA Overview 3
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Origins of SNA
SNA Overview 4
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Plan
&
Collect
RAW DATA:
interview data
survey results
observations
system logs
Collate
Prepare
NETWORK MODEL
INFORMATION:
Data mining results
Entity extraction
Bayesian analysis
Visualise
Analyse
METRICS:
central links
central actors
roles & positions
subgroups
centralisation
SOCIOGRAMS
Interpret
Advise
INTEL & ADVICE:
group structure
lines of influence
stabilisation points
intervention points
options
DYNAMICS:
infer missing data
why links form
growth processes
vulnerabilities
robustness
Simplified SNA process
SNA Overview 5
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• What are you trying to explain?
– variation in success, e.g. performance?
– homogeneity, in attitudes, beliefs or practices?
• Why does tie structure matter? Is it because they are:
– pipes, or
– girders
• What is the currency? Paperbacks, parcels, viruses, ideas, gossip?
– How does each diffuse: is it ‘copied’ or ‘moved’?
– What logic guides the routing of them?
Borgatti, S.P. & Foster, P.C. The Network Paradigm in Organizational Research: …. Journal of Management, 29(6) (2003) 991–1013
Borgatti, S.P., Centrality and Network Flow' Social Networks, 27, (2005) 55-71
Plan: What to ask before conducting an analysis
SNA Overview 6
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Collect
ORGANISATIONAL DATA
called,
emailed,
sought help from,
invited,
met with,
shared a space with,
…
Collect/collate: relationships traced in system logs
SNA Overview 7
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Prepare/Visualise: varieties of actors & relationships
SNA Overview 8
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Data: QinetiQ info
flow questionnaire
Caveat: Borgatti (2005)
On the robustness of
centrality measures under
conditions of
imperfect data, Social
Networks, 28, 2
Analyse: betweenness (centrality) – I…
SNA Overview 9
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DATA:
QinetiQ staff,
ProblemSolving
questionnaire
A
B
Analyse/Interpret: discovering brokers (boundary spanners)
SNA Overview 10
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Jordan, F. personal communication
Analyse: betweenness (centrality) – 7/7 attacks
SNA Overview 11
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Case Study:
JFCOM MNE4
Week 1
[Planning]
IWS m-slice 96:
m-slicing
results:
single network
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Command
Interagency
Group
component
Execution
Planning
Components
Control
Assessment
Knowledge
Support
Interpret: structures & underlying processes
SNA Overview 12
Case Study:
JFCOM MNE4 Assessment
Week 3
[Execution]
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Comp’ts ©integrated;
Inter-agency distrib;
WG appears;
EBP still central
Execut’n on a limb
MNIG gone native.
IWS m-slice 84:
m-slicing
results:
single network
component
Execution
(but, caution…)
Command
Components
Planning
Control
Knowledge
Support
WG
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SNA Overview 13
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Robustness to targeted attack & random failure - rare
Degree Distribution (GT50, N=169)
80
Frequency
70
60
50
40
30
20
10
0
6
12
18 24 30 36 42 48 54 60 66 72 78 84 90 96
Degree (upper bound)
Collaboration tool logs, MNE4 Wk3 (link_wt>50)
IWS (blue), vs. random network (pink):
‘bimodal’ - suggests robustness to both
targeted attack & random failure
Interpret: Assessing robustness: JFCOM experiment: results
SNA Overview 14
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Simulated attack fails to disconnect network
Collaboration tool logs (IWS/Wk3-GT50)
Removal of top 20% (degree) - small increase in diameter
Interpret/Advise: robustness - simulated attack
SNA Overview 15
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Challenges & opportunities in SNA, in these domains
• Difficulties in inferring causality – e.g. groups affect individuals, and vc. vs.
• Dynamic (predictive) modelling: statistical models, simulations
• Multi-modal networks (e.g. documents-people-groups-organisations)
• Missing data / overlapping networks (email vs. chat vs. observations)
• ‘Valued’ links – extracting value from weighted data
• Fragility & over-use of some measures
• Impact of spatial dimension
• Danger of cognitive bias in analysts
• Design and synthesis of networks
• (absence of a) Library of networks (network corpus), for ‘diagnosis’
• Analysis of very large networks
• Analysis tools are academic: powerful, borderline-usable, data formats…
SNA Overview 16
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Network analysis tools (yellow) and formats (blue) !
SNA Overview 17
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