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

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

What is SNA?

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.

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.

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.”

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

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 e-mail, 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.

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

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

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.

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

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?

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.

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.

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