Social Network Analysis: a theory and set of methods focused on the meaning of connections and social structure.
- The point of SNA
- Relationships, and how we connect with one another, matter!
- More so than individual traits or characteristics*
- The way networks are patterned and structured also matters
- Network - A group of individual entities connected in a meaningful way
- Node/Actor/Agent - Individual units
- Edge/Tie/Connection - Defined relationship or connection between nodes
- Directed or undirected
- Reciprocal or not
Attributes vs. Relations
Attributes: What we measure all the time!
- Behavioral variables (e.g., physical activity)
Relations: ties and structures within networks
- Who do you know, talk to, trust, spend time with, etc.
- How closely are you connected to others? How many people are you connected to?
- Is the network you’re apart of dense, hierarchical, clustered and does that matter?
Basic Assumptions that make SNA different
- Independence is NOT assumed
- Actually, that’s an irresponsible way to think, according to network theory
- “The whole is more than the sum of its parts”
- Inputs and outputs
- Variance explained
Why Might We Need SNA?
- Dissatisfaction with attribute theories of behavior
- More realistic modeling of human behavior
- Behaviors and diseases spread through social contacts, so model that
- Develop better programs/interventions
Why Might We Need SNA?
- It’s SUPER interesting!!
- The field is growing and continues to be “written”
- Applies across physical, biological, and social sciences
Two Approaches to SNA
Egocentric Network Research
- Focuses on personal networks of individual people
- The ego is the “hub” of the network
- Constrained by the environments and activities in which the ego is embedded
- Fits well within standard social/behavioral research
Egocentric Network Measures
- Structural Holes
Whole Network Research
- All sets of ties among all members of a given network are studied
- All alters in a whole network are egos, and all egos are alters
- No longer a focal ego
- Allows for individual, group, and network level analysis
Whole Network Measures - Centrality
- A property of a person’s position in a network
- Where does someone “land” in relation to other nodes in a network?
- Central nodes usually carry positions of popularity, power, and prestige
- Centrality typically implies structural importance
- Central nodes often have influence in behavior spread across a network
- Several measures of centrality
- Eigenvector Centrality
Whole Network Measures - Group-Level
- Subset of a network
- Component (most basic): all nodes that can reach one another through any number of steps; nodes that cannot reach one another are in a separate component of the network
- K-core: subset of the network in which each node is connected to at least K other people
- Creates a density factor for groups
- Clique: all members of a group are connected to all members of that group
- SNA posits that people who engage in a particular behavior are often surrounded by other people who also engage in that behavior, or at least approve of doing so
Whole Network Measures - Network-Level
- Calculated on the whole network (as opposed to each node)
- Investigates the network from a global (or bird’s eye) perspective
- Average path length
- Density and Centralization