Network Approaches John D. Prochaska, DrPH, MPH UTMB Department of Preventive Medicine & Community Health

Learning Objectives To define a network and discuss the utility of analyzing networks rather than isolated individuals To present examples of networks in real-world applications To summarize key network measures commonly implemented in network analysis

What is a Network? A structure made up of a set of actors and the dyadic ties among the actors Examples include Social networks Organizational networks Information networks Complex networks of all of the above

Why do Network Analysis Researched to understand the nature of relationships among actors, nodes, or other agents or organizations

Components of a Network? Notes (or vertices) Ties (or edges) Strong (bi-directional, reciprocal) Weak (uni-directional) Pendants Isolates Attribute Data Relational Data

The Internet in 2005

Spatial Network Network of Facebook Friends circa 2006 Source: Wikimedia

Epidemiology / Disease Outbreak

Types of Relationships Similarities Membership Same attitudes towards Spatial location Social Relations Friend of Knows about Relative of Interactions Talked to Helped Flows Information Beliefs Personnel Resources

Network Measures - Individuals Density Centrality Total degree In degree Out degree Closeness Betweeness

Network Measures – Network Level Size Network density Network centrality Reciprocity Efficiency

Applications – Faculty Collaboration Faculty Members that Attend Meetings Together

Applications – Faculty Collaboration Same Group of Faculty Members that Develop Grant Proposals Jointly

Applications – Faculty Collaboration Same Group of Faculty Members that Publish Together

Issues to Consider Who completes the survey and who do they represent What are the boundaries of the network Sampling

Summary Examining networks provides key insight into the workings of a the larger system Provides information beyond what can be gained by examining individuals as separate units Can provide critical information for improving communication, collaboration, and efficiency