1. CS 594: Empirical Methods in HCC Social Network Analysis in HCI

2. Overview Brief History SNA and HCI SNA Research Questions
Performing SNA
Sociometer: Example use of SNA in HCI

3. What is SNA?

4. What is SNA?
A social network consisting of Twitter users ( nodes ) who have tweeted the word “global warming” connected to one another based on Follow, Reply, or Mention relationships ( edges ). Nodes are assigned different colors based on clusters, and hubs with many followers are indicated
by size. Labels for each group are derived from frequently mentioned hashtags in the tweets from the users in each cluster.

5. What is SNA?
Social Network Analysis is the study of different social relationships, which consist of social actors implicitly or explicitly connected to one another.
Focus on relational data between entities rather than attribute data about individuals. E.g., not how one user uses the XYZ s/w, but how users—say, employees ranging across different ranks—work together on a change request using XYZ.

6. What is SNA? SNA --> {entities, relationships}
Entities, e.g.,  people, groups, organizations, artifacts, nodes, vertices
Relationships, e.g., ties, associations, exchanges, memberships, links, edges
SNA is about finding patterns generated within collections of many connections.
E.g.,  for individuals, SNA is more about “who you know” than “what you know” or “who you are.”

7. Why do SNA in HCI?
SNA is relevant in HCI investigations, where the focus is on systems that support interactions between people, or theories and models surrounding it.
Commonly used in CSCW—situated primarily at the intersection of sociology and HCI.
CSCW = Computer supported collaborative work and social computing. E.g., social media systems like Facebook or Twitter

8. Social Networks—then and now
The concept of social networks is not new. It has existed since people have interacted, traded, and engaged with one another.
But the current scale of social networks—and thereby large amounts of data—afforded by the Internet and the rise of  social networking services have led to the widespread interest in SNA
Social networks are present in collections of , instant messaging, text messages, phone call logs, hyperlinks, message forum posts and replies, wiki page edits, tweets, “pins,” video calls, multiplayer games, etc.—opening up new opportunities in computational social science.

9. Types of SNA uses in HCI Social scientists Community administrators
Marketers
Designers of CSCW systems, and
Others..

10. Brief History Foundational phase (18th century to 1970s)
Establishing terms and mathematical graph theory foundation
“six degrees of separation” study by Milgram
Strong ties and weak ties
Computational phase (1970s to mid-1990s)
Computational tools (analyze and visualize networks)
Techniques for identifying subgroups, structural equivalence
Network data deluge phase (current)
SNA is no longer a purely academic exercise, but used in many applications
 SNA techniques are being used to find criminals, rank web sites, recommend books, identify influencers, and restructure organizations.
Tools such as NodeXL and Gephi for visualization

11. SNA and HCI The use of SNA in HCI is recent.
SNA is mostly used to design, evaluate, and understand CSCW and social media systems.

12. Goals of SNA in HCI Answer fundamental social science questions
Inform the design and implementation of new CSCW systems
properties of a target user population can help clarify user requirements
Understand and improve current CSCW systems
Evaluate the impact of CSCW system on social relationships
Design novel CSCW systems and features using SNA methods
E.g.,  a tool that recommends potential friends on a social networking site
 Answer fundamental social science questions

13. SNA Research Questions
The emphasis is on understanding social structures (different units of analysis) and how these structures influence information systems.
About individual social actors
 Who are the most popular individuals in a network?
 If one is trying to disrupt a network, who should be removed?
 Who is a bridge spanner between different subgroups of users?
About overall network structure
How interconnected are a group of social actors (i.e., how dense is the network)?
 Are there subgroups of highly connected users (i.e., clusters, cliques)? If so, how many?
About network dynamics and flows
 How do the structures of social relationship vary over time?

14. Performing SNA Identify goals and research questions Collect data
Types of networks
 Directed Versus Undirected
 Weighted Versus Unweighted
 Multiplex Networks.
 Unimodal and Multimodal Networks
 Partial Networks
 Network data is represented in three primary ways: edge lists, matrices, and graphs
Analyze and visualize data
For example, Facebook includes the obvious friendship network (unimodal, unweighted, undirected), the “people tagged
together” network (unimodal, weighted, undirected), the “wall post” network (unimodal, weighted, directed), and the “person-to-group” network (multimodal,
unweighted, undirected) to name a few. The choice of which networks to focus on depends on the goals of the particular study.

15. Example use of SNA in HCI: Sociometer
Wearable sensors to measure face-to-face interactions.
 Information about people nearby (IR sensor)
 Speech information (microphone)
 Motion information (accelerometer)
SNA to model community interactions
 An initial picture of the network structure can be
obtained by measuring the duration that people are in close
face-to-face proximity using the IR sensor data.
 The link structure of the group based on
duration.

16. Upcoming: Proposal due Sep 26, 11:59pm
Start working on your annotated bibliography
Post your slides on piazza after class presentations