Week 12 - Collective Behavior

Today’s Dad Joke

When I was young, we were really poor. My family could only afford a second-hand calculator, which was missing the “X” button.

Times were hard.

Housekeeping

  • Exam next week
    • Open book / open note / open internet?
    • Short response + multiple choice

Final Project

  • Timing for final project
    • Don’t wait - get started now!
    • Reach out if you get stuck
  • Look at example projects from the past
  • Not all visualizations have to be networks
  • Concepts + Visualizations

Mini-lecture on Wisdom of Crowds and Collective Intelligence

Collective Intelligence

  • Idea that groups can be smarter than the smartest person in the group
  • Sometimes it’s simple; e.g, aggregating information from multiple sources
  • Sometimes there is an emergent property, where the group thinks and behaves differently

Ants

Organizations

  • While organizations are much more hierarchical than ants, they can still have emergent properties
  • Partially a function of history, partially of the structure of the organization
  • Even a culture everyone dislikes can be hard to change
  • E.g., metric system, QWERTY keyboards

Cities

  • High-level decisions about zoning, infrastructure, etc. but the character of a city is emergent
  • Jane Jacobs: “The Death and Life of Great American Cities”

Wisdom of Crowds Activity

  • Get out a piece of paper
  • Guess how many pages are in this book and write down your guess
  • Tell your guess (and no other information) to the two people on either side of you
  • Guess again how many pages are in the book and write it on a new line (Guess 2)

Activity 2

  • Guess 3: Guess the pages in this book
  • Two random people will tell us their guess
  • Guess 4: Guess the pages again for this book

Collective understanding and decision-making

  • Wisdom of crowds is idea that in many contexts, the average is a really good guess!
  • What is groupthink? Have you seen examples? How might this relate?
  • Dr. Josh Becker et al. show that in some cases, communication can help
    • Those whose guesses are worst move the most
    • Divorced from other social relationships (not multiplex)

Results

Decentralized network

Centralized network

Connections to other network concepts

  • How does this relate to our week on small group networks?
    • Transactive memory
    • Hierarchy
    • Centralization
  • How could you design a group / network to get the benefits of the wisdom of crowds?
  • When would you expect a wisdom of crowds approach to work well?
  • When would you expect it to fail?

Plan for Today

  • Exam Review

Exam Review

  • Visualization / ggraph
  • Look at code and explain what it will look like
  • Find the bug in code

Example

  • What code produces this graph?
G |>
  mutate(centrality = centrality_degree()) |>
  activate(edges) |>
  ggraph() +
  geom_edge_fan(color = 'purple') +
  geom_node_point(aes(size = centrality), color = 'green')

Exam Review

What would this code do?

G |>
  activate(nodes) |>
  mutate(ec = centrality_eigen()) |>
  filter(ec > 1) |>
  ggraph() +
  geom_edge_fan(color = 'orange') +
  geom_node_point(aes(size = ec), color = 'green')

Exam Review

  • Centrality
  • Network representations (Edgelists and matrices)
  • Network formation
    • Homophily, focus theory, transitivity, social exchange theory, etc.
  • Tie strength and small worlds

Exam Review

  • Power and social capital
  • Contagion and diffusion
  • Centrality
  • Resilience
  • Bipartite networks and projections

Exam Review

  • Friendship paradox
  • Strength of weak ties