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Network Analysis

The Hidden Structures behind the Webs We Weave
17-338 / 17-668 | Fall 2024

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Network wormholes in Singapore’s Twitter network, from Park et al, Science 2018. “Each dot represents an individual, and each edge represents a bidirected @mention. Nodes and edges are colored according to membership in distinct network communities. A sample of network wormholes (with range six or above and above-median tie strength) is shown in yellow. The inset highlights a single wormhole of range eight, i.e., the second-shortest path between the yellow nodes requires traversing eight intermediary ties (blue edges). The sizes of the nodes in the inset are proportional to the number of network neighbors.”

Overview

Why does Linux and the broader open-source ecosystem thrive despite weak economic incentives? Why do complex software systems sometimes fail despite being well-engineered? What makes a social media recommendation algorithm so effective and so toxic at the same time? Why do YouTube mega-influencers with tens of millions of subscribers exist, yet each of us can only recognize a handful at best? How do echo chambers and polarization emerge in social media platforms? How can you land your dream jobs? How does mass adoption of technological innovations happen? Underlying these seemingly unrelated questions is the powerful influence of social networks, the collection of on- and offline connections and dependencies that people and systems form with one another, often unknowingly.

This course offers an introduction to the study of social networks and builds the skills needed to answer these wide range of questions by interweaving two threads. First, we introduce network science concepts and their mathematical and graph theoretical foundations, to give rigorous definitions to fuzzy words we use to describe the social world, such as “status” and “social group.” Second, we apply these network concepts hands-on, to statistically model and study a wide range of puzzling online social phenomena in real-world networks.

After completing this course, you will be able to:

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Course Syllabus and Policies

The syllabus covers course overview and objectives, evaluation, time management, late work policy, and collaboration policy.

Schedule

Below is a preliminary schedule for Fall 2024. The schedule is subject to change and will be updated as the semester progresses. For previous schedules, see Fall 2023.

Date Topic Notes Song of the Day
Tue, Aug 27 Introduction slides  
Thu, Aug 29 Intro to graph theory slides Connected (Stereo MCs)
Tue, Sep 3 Random networks slides One (U2)
Thu, Sep 5 Edges vs social ties slides In My Life (The Beatles)
Tue, Sep 10 Triads and structural balance slides You Belong With Me (Taylor Swift)
Thu, Sep 12 From social processes to graphs slides We Are Never Ever Getting Back Together (Taylor Swift)
Tue, Sep 17 Homophily and degree correlation (part 1) slides Birds of a Feather (Billie Eilish)
Thu, Sep 19 Homophily and degree correlation (part 2) slides Cowbody Like Me (Taylor Swift)
Tue, Sep 24 Power and centrality in social networks slides Everybody Wants to Rule the World (Tears for Fears)
Thu, Sep 26 Power and centrality in social exchange slides No Scrubs (TLC)
Tue, Oct 1 Detecting communities slides We Are Family (Sister Sledge)
Thu, Oct 3 Structural equivalence slides Where Do You Belong? (Mean Girls the Musical)
Tue, Oct 8 Affiliations and overlapping subgroups slides With a Little Help From My Friends (The Beatles)
Thu, Oct 10 Midterm exam    
Tue, Oct 15 Fall break, no class    
Thu, Oct 17 Fall break, no class    
Tue, Oct 22 Network Analysis of Open Source Software slides  
Thu, Oct 24 Visualizing network data slides  
Tue, Oct 29 Scale-free networks slides All Star (Smashmouth)
Thu, Oct 31 Network inequality slides God Bless the Child (Billie Holiday)
Tue, Nov 5 Democracy Day, no class    
Thu, Nov 7 Small-world networks [slides] It’s a Small World (Disney)
Tue, Nov 12 Social Capital (part 1) [slides] I Heard It Through the Grapevine (Marvin Gaye)
Thu, Nov 14 Social Capital (part 2) [slides] Bad Blood (Taylor Swift)
Tue, Nov 19 Diffusion and contagion [slides] Word of Mouth (Mike + The Mechanics)
Thu, Nov 21 Ethical issues [slides] Royals (Lorde)
Tue, Nov 26 Exemplary studies [slides] The Man (Taylor Swift)
Thu, Nov 28 Thanksgiving, no class    
Tue, Dec 3 Guest lecture: Kathleen Carley    
Thu, Dec 5 Final Project Presentations   We’re All in This Together (High School Musical)