Events
Past Event
WED@NICO SEMINAR: Johan Koskinen, University of Manchester "Modelling large, messy, and sampled network data"
Northwestern Institute on Complex Systems (NICO)
12:00 PM
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Lower Level, Chambers Hall
Details
Title:
Modelling large, messy, and sampled network data – problems and prospects for principled analysis of real social networks
Speaker:
Johan Koskinen - Lecturer in Social Statistics, Cathie Marsh Institute for Social Research, University of Manchester
Talk Abstract:
The social network analysis (SNA) paradigm has proved a powerful and intuitive explanatory perspective that has recently gained new currency under the more general moniker of network science. SNA draws on graph theory and social entities are conceived of as nodes in a graph connected by lines (or edges), representing how people, organisations, countries, etc. are relationally tied. Having a network perspective results in compelling pictures of the social web; insightful summary measures capturing both positions of individuals and properties of the network; as well as the possibility of statistical modelling of how nodes are connected. Here we consider the latter - statistical modelling of the network. In particular we are considering modelling tie-variables using exponential random graph models (ERGM). ERGMs have their origin in statistical mechanics and are intimately related to Markov random fields and the classic Ising and Potts models. For social networks, in contrast to, say, particle spins on a lattice, the modelling often turns out to be much more complicated but also giving rise to richer models. Here we discuss some issues associated with modelling social networks based on empirical data. Among the challenges of this domain are specifying the boundary of the network and accounting for the often partial nature of data. Additionally, seeing as social networks cannot typically be collected automatically (through for example scraping on-line sources), we have to rely on observational data that is often laden with error. Among the opportunities that real social network data offers is that you may explore the full complexity of people’s relations. People are not only tied to other people but also affiliated with organisations, places, and events. We present these different aspects in the context of a number of illustrative datasets where information is collected and collated from different sources.
Speaker Bio:
Johan Koskinen joined the Department of Social Statistics at the University of Manchester in 2011 having previously worked at the Universities of Stockholm, Melbourne and Oxford. Dr Koskinen has contributed extensively to methodological development in social network analysis to enabled innovative applications by several disciplines. He is one of the co-authors of the RSiena statistical network analysis package for longitudinal network analysis and a contributor to the MPnet software package, one of the most commonly used statistical software packages for network analysis. His methodological contributions are often developed in collaboration over substantive research projects with applied researchers and he is active in disseminating best practices through frequent workshops. He has also co-written two books on social network research methods aimed at practitioners. One of them a book on exponential random graph models (Cambridge University Press) that was awarded the 2016 Harrison White Book Award by the American Sociological Association. His current research concentrates on extending current statistical methodology for modelling social interaction to social networks of multiple types of nodes using data collated and collected from different sources
Live Stream:
Time
Wednesday, September 27, 2017 at 12:00 PM - 1:00 PM
Location
Lower Level, Chambers Hall Map
Contact
Calendar
Northwestern Institute on Complex Systems (NICO)
WED@NICO SEMINAR: Lightning Talks w/ Northwestern Scholars!
Northwestern Institute on Complex Systems (NICO)
12:00 PM
//
Lower Level, Chambers Hall
Details
Speakers:
Yessica Herrera, Visiting Scholar, Northwestern Institute on Complex Systems
Talk Title: The Body Speaks: Visual Patterns of Psychological Stress
Aakriti Kumar, Post-Doctoral Fellow, Northwestern Institute on Complex Systems
Talk Title: Evaluating Elements of Empathic Communication with Experts, Crowds, and Large Language Models
Tingyu "Mark" Zhao, PhD Student, Industrial Engineering and Management Sciences
Talk Title: Noise Filtering in Complex Networks
Sign Up:
Sign up to present at a future Lightning Talk session. NICO Lightning Talks are open to graduate students, postdoctoral fellows, and visiting scholars.
Location:
In person: Chambers Hall, 600 Foster Street, Lower Level
Remote option: https://northwestern.zoom.us/j/95387714084
Passcode: NICO25
About the Speaker Series:
Wednesdays@NICO is a vibrant weekly seminar series focusing broadly on the topics of complex systems, data science and network science. It brings together attendees ranging from graduate students to senior faculty who span all of the schools across Northwestern, from applied math to sociology to biology and every discipline in-between. Please visit: https://bit.ly/WedatNICO for information on future speakers.
Time
Wednesday, May 14, 2025 at 12:00 PM - 1:00 PM
Location
Lower Level, Chambers Hall Map
Contact
Calendar
Northwestern Institute on Complex Systems (NICO)
WED@NICO SEMINAR: Rosemary Braun, Northwestern University "The Scale of Life"
Northwestern Institute on Complex Systems (NICO)
12:00 PM
//
Lower Level, Chambers Hall
Details
Speaker:
Rosemary Braun, Associate Professor, Department of Molecular Biosciences, Northwestern University
Title:
The Scale of Life
Abstract:
Living systems exhibit surprising and beautiful self-organization at all scales. At the atomic level, proteins self-assemble into macromolecular complexes. The function of these machines is orchestrated within the cell by regulatory networks, whose activity is in turn dictated by, and coordinated with, the cells environment. This coordination takes place across large spans of space and time: the size and lifetime of organisms as large as the blue whale. Populations and ecosystems of many organisms in turn exhibit remarkable emergent dynamics. Today, advances in single-cell assays enable us to probe the molecular state of every cell in a sample in high-dimensional detail. But is this the correct scale at which to probe living systems? What can we learn from this data, and how can we abstract from the microscopic details to macroscopic phenotypes? In this talk, I will discuss some of our recent work bridging the cell and tissue/organism scales, and discuss some challenges and opportunities for the future.
Speaker Bio:
Rosemary Braun is an Associate Professor of Molecular Biosciences, Applied Mathematics [ESAM], and Physics at Northwestern University. A theoretical physicist by training, she earned her PhD in Physics from the University of Illinois, followed by a Masters in Biostatistics from Johns Hopkins University. She completed her postdoctoral training at the National Cancer Institute (NIH) before joining Northwestern as a faculty member. Today, she works at the intersection of statistics, mathematics, and biology to develop computational tools for analyzing high-dimensional data. In addition to her Northwestern affiliations, she is also Associate Director of the National Institute for Theory and Mathematics in Biology, as well as external faculty of the Santa Fe Institute.
Location:
In person: Chambers Hall, 600 Foster Street, Lower Level
Remote option: https://northwestern.zoom.us/j/97015976754
Passcode: NICO25
About the Speaker Series:
Wednesdays@NICO is a vibrant weekly seminar series focusing broadly on the topics of complex systems, data science and network science. It brings together attendees ranging from graduate students to senior faculty who span all of the schools across Northwestern, from applied math to sociology to biology and every discipline in-between. Please visit: https://bit.ly/WedatNICO for information on future speakers.
Time
Wednesday, May 21, 2025 at 12:00 PM - 1:00 PM
Location
Lower Level, Chambers Hall Map
Contact
Calendar
Northwestern Institute on Complex Systems (NICO)