[Colloq] Hiring Talk: Zack Almquist - Population Dynamics and Network Dynamics: A Holistic Approach - 2/21 4:30pm

[Jessica Biron]

Population Dynamics and Network Dynamics: A Holistic Approach 


Zack Almquist 


Thursday, February 21st 
4:30-5:45 pm 
Holmes Hall – 540 


Abstract: 


Change in group size and composition has long been an important area of research in the social sciences. Similarly, interest in interaction dynamics has a long history in sociology and social psychology. However, the effects of endogenous group change on interaction dynamics is a surprisingly understudied area. One way to explore these relationships is through social network models. Network dynamics may be viewed as a process of change in the edge structure of a network, in the vertex set on which edges are defined (the population), or in both simultaneously. Though early studies of such processes were primarily descriptive, recent work on this topic has increasingly turned to formal statistical models. While showing great promise, many of these modern dynamic models are computationally intensive and scale very poorly in the size of the network under study and/or the number of time points considered. Likewise, currently employed models focus on edge dynamics, with little support for endogenously changing vertex sets/populations. Here, we show how an existing approach based on logistic network regression can be extended to serve as a highly scalable framework for modeling large networks with dynamic vertex sets. We place this approach within a general dynamic exponential family (ERGM) context, clarifying the assumptions underlying the framework (and providing a clear path for extensions), and show how model assessment methods for cross-sectional networks can be extended to the dynamic case. Examples of phenomena to be discussed include: (1) sexual contact networks (simulated), (2) organizational collaboration networks (disaster response during Hurricane Katrina) and (3) small group interaction networks (face-to-face communication on a beach in Southern California). Finally, we apply this model to the small group interaction example, demonstrating the importance of simultaneously modeling both vertex/population dynamics (who shows up?) and network dynamics (who interacts with whom?). 


Bio: 
Zack Almquist is a doctoral candidate in Sociology at the University of California, Irvine. 
Almquist has MA degrees in Sociology and Demography from UCI, a MS in Statistics 
from Northwestern University, and a BS in Mathematics from the University of Oregon. 
Currently, he is a Graduate Student Researcher for Professor Carter T. Butts, a member 
of the Networks, Computation, and Social Dynamics (NCASD) Lab, and a Graduate 
Student Fellow in the Center for Networks and Relational Analysis. His research lies at 
the intersection of sociology, social network analysis, and demography and has been 
published (or forthcoming) in such journals as Sociological Methodology, the Journal of 
Statistical Software, Demographic Research, and Social Networks. 






Jessica Biron 
Administrative Assistant – Office of the Dean and CCIS Development 
College of Computer and Information Science 
Northeastern University 
202 West Village H 
617-373-5204 
bironje at ccis.neu.edu 
http://www.ccs.neu.edu/