strong and weak ties
Chapter 3. Strong and Weak Ties
MI 302
September 22
Recap of the last week
Graph theory—understanding of a social network at the structure level
Graph
Node
Edge
Path
Connectivity—centrality
Components, giant components
Distance - small world phenomena
Sources and kinds of data
Why does ”connectivity” matter?
The fact that two giant components cannot co-exist
Distance is much shorter than we think
Figure 2.6 Collaboration graph
Learning Goals for Today
Grasp the “strength” of weak ties (Granovetter)
Understand the magnitude of “social capital”
Why do the majority of people get job info from acquaintances?
Reason 1: Benefits stemming from the network structure for a weak tie: Bridging property
Reason 2: Benefits stemming from the properties of “weak ties”: Social capital
=> The two main topics of Today’s class
Triadic Closure
Definition: If a node A has edges to nodes B and C, then the B-C edge is especially likely to form if A’s edges to B and C are both strong ties. Why?
Reason for triadic closure
Opportunity for B and C to meet
Trusting between B and C
Incentives of A
Clustering coefficient
0 coefficient 1
In a network with a high clustering coefficient, a person’s friends tend to know one another
Strengths of Weak Ties
Bridge and local bridge
Strong triadic closure property
Local bridges and weak ties
Reason 1 for the “strength” of weak ties
The definition of a local bridge implies that an edge is a local bridge when it does not form a side of any triangle in the graph.
Doesn’t it contract the triadic closure?
Figure 3.3
Figure 3.4
The strong triadic closure property
Different levels of strength in the edges of a social network
There is not yet a unanimous definition of a ”strength” of an edge. Why?
Stronger links represent closer friendship and greater frequency of interaction.
Strong ties (the stronger links, e.g., friends)
Weak ties (the weaker links, e.g., acquaintances)
Figure 3.5
Local Bridges and Weak Ties
If a node A in a network satisfies the Strong Triadic Closure Property and is involved in at least two strong ties, then any local bridge it is involved in must be a weak tie.
In other words, assuming the Strong Triadic Closure Property, the local bridges in a network are necessarily weak ties.
Because if it weren’t, triadic closure would tend to produce short-cuts to A and B that would eliminate its role as a local bridge.
Figure 3.6
Weak ties connect us to new sources of information and new opportunities. Reason 1 for the “strength” of weak ties
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Tie Strength of Network Structure in Large-Scale Data
Does this really hold in the real world?
Generalized definition of a local bridge in a large network
Local bridges are indeed VERY rare (due to the triadic closure, and that’s why they are valuable!)
The need to loosen the definition of local bridges based on the ratio of the network overlap of an edge between A and B
0 Ratio
When ratio is 0: The edge is a local bridge
Empirical results on tie strength and Neighborhood overlap
Figure 3.7
Tie strength
Overlap
Structure and tie strengths in mobile communication networks
J.P. Onnela, J. Saramäki, J. Hyvönen, G. Szabó, D. Lazer, K. Kaski, J.Kertész, A.-L. Barabási; Proceedings of the National Academy of Sciences May 2007, 104 (18) 7332-7336; DOI:10.1073/pnas.0610245104
Shrinkage of a giant component
Shrinkage of the cellular network
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Tie strength, social media, and passive engagement
Social media increased these weak ties in the society, contributing to the increases in connectivity among people
Marlow’s Facebook study
if the user both sent messages to the friend at the other end of the link, and also received messages from them during the observation period.
if the user followed information about the friend at the other end of the link; “following information on News Feed or visiting the friend’s profile more than once.
if the user sent one or more messages to the friend at the other end of the link
Why does “maintained relationship” (weak ties) matter?
Twitter—especially suitable for maintaining weak-ties
Passive engagement
Lurking
Newsfeed
Following
Subscribing
Bonus slides (updated observations)
Influence marketing (many individuals become influencers)
A type of micro-celebrity (Senft, 2008) who have accrued a large number of followers on social media and frequently use this social capital to gain access to financial resources (Abidin, 2015).
Examples?
Natalia Levsina: https://www.instagram.com/nata_allbuenothings/?utm_source=ig_embed
Rachel Hollis:
https://www.instagram.com/msrachelhollis/?hl=en
Shishi.Rose
https://www.instagram.com/shishi.rose/?hl=en
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What tools are Influencers using?
Authenticity
Creative content
Weak ties
Effectively increase followers’ engagement with the brand
Structural holes
Boundary-spanning edge (mostly weak ties)
Advantages? Innovation and creativeness, brokerage
Reason 2 for the "strength" of weak ties:
Social capital: Includes social network ties and a resource or benefit component from those ties at either the individual actor or collective level, according to Oxford bibliographies.
Human capital as opposed to physical capital
Cultural capital as opposed to economic capital (Bourdieu)
Weak ties can control the flow of information and synthesize it in new ways. Reason 1 for the “strength” of weak ties
Figure 3.11
Structural hole from the organizational perspective
Bridging as Forms of Social Capital
Social capital can be a property of a group or a property of an individual
Some based on the advantages of strong ties
More based on the advantages of weak ties
Example? https://www.thnk.org/insights/thnk-view-social-capital-and-profitability/
Closure and Embeddedness
Embeddedness
Flip side of the advantages of a local bridge
What is it?
Equal to the numerator in the ratio that defines the neighborhood overlap in Equation (3.1) from Section 3.3.
What are the properties of embeddedness?
Reciprocal relationships, trust, reputational consequences
Figure 3.11
Tradeoffs
| Strong Ties | Weak Ties |
| Embeddedness | Boundary-spanning |
| Bonding capital | bridging capital |
| Trust, confidence, protection | Innovation, creativeness, competitive advantage |
Key Takeaways of Today’s Class
What are the two reasons that people get the information about their jobs from acquaintances not from their close friends?
Due to the “strengths” of weak ties
What are the strengths of weak ties?
Benefit 1: Weak ties connect us to new sources of information and new opportunities. => stemming from a triadic closure property
Benefit 2: Those who function as local bridges can control the flow of information and synthesize it in new ways that lead to creativity and innovation. => leading to the accumulation of social capital (which can be defined based on both strong and weak ties’ advantages)
Discussion Question
Describe the reasons that new employees have obtained the information about the jobs from acquaintances, not from close contacts. Be sure to describe these reasons based on the notions of triadic closure property and social capital.
Thursday Recitation
Do hands-on exercises for triadic closure
Strong ties vs. weak ties
Continue to work on the export network and apply the property of a triadic closure to the export network.