Events
Past Event
WED@NICO SEMINAR: Zhimei Ren, University of Chicago "Policy learning 'without' overlap: Pessimism and generalized empirical Bernstein's inequality"
Northwestern Institute on Complex Systems (NICO)
12:00 PM
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Lower Level, Chambers Hall
Details
Speaker:
Zhimei Ren, Postdoctoral Researcher, Statistics Department, University of Chicago
Title:
Policy learning 'without' overlap: Pessimism and generalized empirical Bernstein’s inequality
Abstract:
We study offline policy learning, which aims at utilizing observations collected a priori (from either fixed or adaptively evolving behavior policies) to learn an optimal individualized decision rule that achieves the best overall outcomes for a given population. Existing policy learning methods rely on a uniform overlap assumption, i.e., the propensities of exploring all actions for all individual characteristics are lower bounded in the offline dataset; put differently, the performance of the existing methods depends on the worst-case propensity in the offline dataset. As one has no control over the data collection process, this assumption can be unrealistic in many situations, especially when the behavior policies are allowed to evolve over time with diminishing propensities for certain actions.
In this talk, I will introduce a new algorithm that optimizes lower confidence bounds (LCBs) -- instead of point estimates -- of the policy values. The LCBs are constructed using knowledge of the behavior policies for collecting the offline data. Without assuming any uniform overlap condition, we establish a data-dependent upper bound for the suboptimality of our algorithm, which only depends on (i) the overlap for the optimal policy, and (ii) the complexity of the policy class we optimize over. As an implication, for adaptively collected data, we ensure efficient policy learning as long as the propensities for optimal actions are lower bounded over time, while those for suboptimal ones are allowed to diminish arbitrarily fast. In our theoretical analysis, we develop a new self-normalized type concentration inequality for inverse-propensity-weighting estimators, generalizing the well-known empirical Bernstein's inequality to unbounded and non-i.i.d. data.
Speaker Bio:
Zhimei Ren is a postdoctoral researcher in the Statistics Department at the University of Chicago, advised by Professor Rina Foygel Barber. Starting in July 2023, Zhimei will be an Assistant Professor in the Department of Statistics and Data Science at the Wharton School, University of Pennsylvania. Zhimei's research interests lie broadly in the span of multiple hypothesis testing, survival analysis, distribution-free inference and data-driven decision-making.
Location:
In person: Chambers Hall, 600 Foster Street, Lower Level
Remote option: https://northwestern.zoom.us/j/97028972274
Passcode: NICO23
About the Speaker Series:
Wednesdays@NICO is a vibrant weekly seminar series focusing broadly on the topics of complex systems and data 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, April 19, 2023 at 12:00 PM - 1:00 PM
Location
Lower Level, Chambers Hall Map
Contact
Calendar
Northwestern Institute on Complex Systems (NICO)
WED@NICO SEMINAR: Nicole Woitowich, Feinberg School of Medicine "Exploring the Science of Biomedical Science from Discovery to Impact"
Northwestern Institute on Complex Systems (NICO)
12:00 PM
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Lower Level, Chambers Hall
Details
Speaker:
Nicole Woitowich, Research Assistant Professor, Department of Medical Social Sciences, Feinberg School of Medicine, Executive Director, NUCATS
Title:
Exploring the Science of Biomedical Science from Discovery to Impact
Abstract:
This presentation explores the biomedical research enterprise from a science of science perspective, focusing on the relationships between research practices, the people who shape them, the policies that govern them, and the public they ultimately aim to serve. A central thread of this work examines the intersection of sex and gender inclusion in research, the advancement of women in science and medicine - and how they may be inextricably related. This talk will explore how sex and gender are included, analyzed, and reported in biomedical research, and how gender disparities within the scientific workforce influences the types of questions asked and how data are reported and analyzed. Together, these dynamics have significant implications for the rigor and reproducibility of research, as well as for health outcomes more broadly. The talk will also reflect on how this science of science perspective can inform ongoing work at Northwestern’s Clinical and Translational Sciences (NUCATS) Institute which aims to improve, innovate, and implement generalizable solutions that enhance the efficiency, quality, and impact of clinical and translational science. The session will conclude with an overview of NUCATS’ initiatives and resources aligned with these goals.
Speaker Bio:
Nicole (Niki) Woitowich, PhD, is the Executive Director of the Northwestern University Clinical and Translational Sciences (NUCATS) Institute and a Research Assistant Professor in the Department of Medical Social Sciences at the Feinberg School of Medicine. Her work focuses on advancing women's health and the representation of women in science and medicine, aiming to transform the biomedical research landscape through her research, advocacy, and outreach.
Trained as a biochemist, Dr. Woitowich earned her PhD in Biochemistry and Molecular Biology from Rosalind Franklin University of Medicine and Science. She has specialized knowledge in neuroendocrinology, reproductive physiology, and enzymology. Her current research investigates the intersections of sex and gender in biomedicine, from research policy to practice, emphasizing the importance of considering sex as a biological variable and the inclusion of women in the biomedical research workforce.
Dr. Woitowich holds a longstanding interest in science policy. In 2016, she was awarded the Presidential Management Fellowship. She continues to advocate for women's health research and played a key role in establishing January 25th as Women’s Health Research Day.
Committed to making science accessible, Dr. Woitowich collaborates with researchers nationwide to enhance their communication and public engagement skills. She holds leadership positions within the American Society for Biochemistry and Molecular Biology and the non-profit organization Women’s Health Access Matters (WHAM).
Location:
In person: Chambers Hall, 600 Foster Street, Lower Level
Remote option: https://northwestern.zoom.us/j/95817534965
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, April 30, 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: Diego Gomez-Zara, University of Notre Dame "All-Female and Female-Led Teams Drive More Breakthrough Ideas in Science and Innovation"
Northwestern Institute on Complex Systems (NICO)
12:00 PM
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KGH2410, Kellogg Global Hub
Details
Speaker:
Diego Gómez-Zará, Assistant Professor, Department of Computer Science and Engineering, University of Notre Dame
Title:
All-Female and Female-Led Teams Drive More Breakthrough Ideas in Science and Innovation
Abstract:
The increase of female researchers in science over the past decades has initiated many studies on the gender composition of teams and their research outcomes. Substantial evidence underscores the value of including female researchers in science. Yet, their impact on driving new research directions and technological innovation within teams remains underexplored. In this presentation, we analyze over 65 million papers and two million patents spanning 1950-2010. We document the rise in all-female teams and demonstrate that all-female teams consistently produce the highest proportion of disruptive papers. We explore this trend across time periods, team sizes, and fields. We find that despite the overall decline in disruption, notably, all-female teams have the smallest decline in disruption. We analyze publication text, field-specific structural differences, author careers, leadership dynamics, and team dynamics to understand the vital role that all-female teams play in driving breakthroughs.
Speaker Bio:
Diego Gómez-Zará is an Assistant Professor of Computer Science and Engineering at the University of Notre Dame. His research focuses on how social computational systems help people organize and collaborate. His work has been at the forefront of computational social science, human-computer interaction, and network science. Before joining Notre Dame, he was a postdoctoral fellow at Northwestern University's Kellogg School of Management and received his Ph.D. in Technology and Social Behavior at Northwestern University. His recent publications include work in recommender systems, team formation, diversity, and virtual reality. This research has won best paper awards at top conferences in human-computer interaction, including CHI, CSCW, and IUI. His research has been supported by the Alfred P. Sloan Foundation, DARPA, National Science Foundation, Microsoft Research, IBM, Amazon Research, and Slack Inc.
Location:
NOTE: LOCATION CHANGE THIS WEEK
In person: Kellogg Global Hub, 2211 Campus Drive, KGH2410
Remote option: https://northwestern.zoom.us/j/97630539917
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 7, 2025 at 12:00 PM - 1:00 PM
Location
KGH2410, Kellogg Global Hub 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
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Lower Level, Chambers Hall
Details
Sign Up:
Sign up to present at our spring 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
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:
TBA
Abstract:
TBA
Speaker Bio:
Rosemary Braun is an Associate Professor of Molecular Biosciences, Applied Math, and Physics at Northwestern University. Driven by a desire to understand how living systems self organize across scales, she conducts research at the interface between mathematics and biology. Her computational laboratory develops novel machine-learning methods for the statistical analysis of high-dimensional data; graph-theoretic approaches to describe the behavior of interaction networks; and dynamical simulations to model how cellular processes are coordinated in time. She collaborates extensively to apply these methods to diverse biological processes, including development, sleep, and cancer. A physicist by training, Rosemary obtained her BSc in Physics from SUNY Stony Brook and Ph.D. in Physics from from the University of Illinois at Urbana-Champaign in 2004. Following her PhD, she obtained an MPH in Biostatistics from Johns Hopkins University and was a Cancer Prevention Postdoctoral Fellow at the National Cancer Institute (NIH).
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)