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Social Network Theory

Dr. Zaheeruddin Asif

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What is a Network?

• Nodes• Relationships• Properties– Directional – Symmetric– Flow– Mulitplexity

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Nodes

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Relationships

• Directional• Friendship• Advice seeking• Buyer/supplier

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Relationships

• Symmetric• Strategic alliance• Club membership• Co-authorship

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Transitivity

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Reciprocity

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Network Scope

• Ego-centric• Socio-centric• Open-system

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Socio-centric

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Combined ego-networks of five active authors

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Centrality

• Degree centrality: "An important node is involved in large number

of interactions“

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Centrality

• Closeness centrality: "An important node is typically “close” to, and

can communicate quickly with, the othernodes in the network. “

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Centrality

• Betweenness centrality: "An important node will lie on a high proportion of paths between other nodes in the network."

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Hubs and Bridges

Betweenness = Size

(in-degree)

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Closeness Centrality

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Betweenness Centrality

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Theories of Networks

• Social Capital• Structural Holes• Social Exchange• Collective Action• Cognitive theories• Homophily theories

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Social Capital

• Pierre Bourdieu

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Social Capital

• Pierre Bourdieu• "the sum of the resources, actual or virtual,

that accrue to an individual or a group by virtue of possessing a durable network of more or less institutionalized relationships of mutual acquaintance and recognition"

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Social exchange• Social exchange or dependence theories hold

that people form ties with whom they can exchange resources, and only those ties that are mutually beneficial will be sustained over time.

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Propinquity

• Geographically close nodes are more likely to be connected.

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Homophily

• Pairs can be said to be homophilous if they their characteristics match in a proportion greater than expected in the population from which they are drawn or the network of which they are a part (Verbrugge 1977).

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Homophily

• Homophily theories claim that people form ties with those they consider similar to themselves.

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References

• http://www.commetrix.de/IRIS• http://www.oecd.org/dataoecd/7/23/418586

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