Network Analysis of the local Public Health Sector: Translating evidence into practice

Network Analysis of the local Network Analysis of the local Public Health Sector: Public Health Sector:

Translating evidence into practiceTranslating evidence into practice

Helen McAneneyHelen McAneney

School of Medicine, Dentistry and Biomedical Sciences,School of Medicine, Dentistry and Biomedical Sciences,Queen’s University BelfastQueen’s University Belfast

Early beginnings for Social Network Analysis

• Stanley Milgram and six degrees of separation– the Erdös number and

the Kevin Bacon game

• Granovetter (1973):

– “The strength of weak ties”

• Watts and Strogatz (1998):

– “Collective dynamics of small-world networks” Euler’s Konigsberg's

Bridges Problem (1736)

Applications

• Knowledge transfer

• Disease transfer

– STDs

– Avian flu (hub airports)

• Drugs/smoking/obesity

• Web, Google

• Citations of articles

• Neighbourhood effects

The shape of the US purely from the flight paths.

SNA Theory

• Nodes (actors) and edges (ties)• Adjacency matrix A• SNA measures

– Centrality, centralisation, block-modelling• Freeman Degree Centrality

– No. of edges attached to it

– Normalised Degree

n

jiji Ak

1

maxkki

SNA Theory

• Bonacich Eigenvector Centrality – Edges weighted by influence of node connected to

– is largest e-value, x is e-vector of A

• Betweenness Centrality– Fraction of geodesic paths that a given node lies on– Control a node has over flow of information

n

jjiji xAx

1

1

A few examples: Star network

• Star network

• Adjacency matrix of

0000001000000100000010000001000000100000011111110

STARA

A few examples: Star network

• Centrality measures

– Freeman Degree

– Bonacich Eigenvector

– Betweenness

• Centralisation 100%, node1 dominates

Node Degree Eigenvector Betweenness 1 6 0.707 15 2 1 0.29 0 3 1 0.29 0 4 1 0.29 0 5 1 0.29 0 6 1 0.29 0 7 1 0.29 0

A few examples: Circle network

• Circle network

• Adjacency matrix of

0100001101000001010000010100000101000001011000010

CIRCLEA

A few examples: Circle network

• Centrality measures

– Freeman Degree

– Bonacich Eigenvector

– Betweenness

• Centralisation 0%, all nodes equal

Node Degree Eigenvector Betweenness 1 2 0.38 3 2 2 0.38 3 3 2 0.38 3 4 2 0.38 3 5 2 0.38 3 6 2 0.38 3 7 2 0.38 3

A few examples: Line network

• Line network (‘broken circle’)

• Adjacency matrix of

0010000000100010001000100010001000100010010000110

LINEA

A few examples: Line network

• Centrality measures

• Centralisation

– 6.67% (degree)

– 39% (e-vector)

– 31% (betweenness)

Node Degree Eigenvector Betweenness 1 2 0.50 9 2 2 0.46 8 3 2 0.46 8 4 2 0.35 5 5 2 0.35 5 6 1 0.19 0 7 1 0.19 0

CoE Network in Public Health

• Launch of UKCRC CoE in Public Health (NI) June 2008

• Questionnaire to provide baseline data

• Create a map of PH community in NI

• 98 participants from 44 organisations & research clusters

• 193 nodes (organisations) nominated

How personal goals related to those of CoE

CoE Network in Public Health

193 organisations and research clusters

• Centrality measures

• Centralisation

– 16% (out-degree) & 5% (in-degree)

– 51% (eigenvector)

– 4% (betweenness)

Out-Degree In-Degree Eigenvector Betweenness 1. QUB_CCPS DHSSPS BHSCT DHSSPS 2. EHSSB BHSCT DHSSPS BHSCT 3. NICR IPH QUB_CCPS QUB_NM 4. DHSSPS HSCT UU UU 5. QUB_NM QUB EHSSB IPH 6. BHSCT UU RDO RDO

Block-model of Network

Block-model of Network

Root mean square of impact and strength

Values of 1 (high) – 3 (low)Strongest if 2 (1+1), weakest if 6 (3+3)

Questions for the future

• Identified difference in attitudes/goals of academics & non-academics.

• Sectors with little or no interaction• Influential organisation

– good or bad?• ‘Value’ of trans-disciplinary interaction• CoE’s translational message,

– improving cross collaboration– improving effectiveness for clinical or PH outcomes

Acknowledgement

• Dr Jim McCann

– School of Mathematics and Physics

• Prof. Lindsay Prior

– School of Sociology, Social Policy and Social Work,

• Jane Wilde CBE

– The Institute of Public Health in Ireland

• Prof. Frank Kee

– Director UKCRC Centre of Excellence for Public Health

– www.qub.ac.uk/coe