Identifier,"Start Date / Time","End Date / Time",Title,Subtitle,Type,Description,Permalink,"Building Name",Room,"Location Name",Cost,Tags,Sponsors
110530-21825018,"2023-09-06 11:00:00","2023-09-06 12:00:00","HET Brown Bag Seminar | Generalized entropy for general subregions in quantum gravity","Antony Speranza (UIUC)","Lecture / Discussion","I will describe a construction of algebras of observables associated with local subregions in quantum gravity in the small G_N limit. This algebra consists of operators dressed to a semiclassical observer degree of freedom which serves as an anchor defining the subregion. I will argue that properly implementing the gravitational constraints on this algebra results in a type II von Neumann algebra, which possesses a well-defined notion of entropy. Up to a state-independent constant, this entropy agrees with the UV-finite generalized entropy of the subregion, consisting of a Bekenstein-Hawking area term and a bulk entropy term. This gives an algebraic explanation for the finiteness of the generalized entropy, and provides a number of tools for investigating aspects of semiclassical gravitational entropy, including the generalized second law, the quantum focusing conjecture, and the quantum extremal surface prescription in holography.",https://events.umich.edu/event/110530,"Randall Laboratory",3481,"Randall Laboratory",,"brown bag","Leinweber Center for Theoretical Physics
Department of Physics
HET Brown Bag Series
Leinweber Center for Theoretical Physics Seminars
Leinweber Center for Theoretical Physics Brown Bag Seminars"
111380-21826916,"2023-09-13 11:00:00","2023-09-13 12:00:00","Brown Bag Seminar | Physical Signatures of Fermion-Coupled Axions","Alex Millar (Fermilab)","Lecture / Discussion","While there is an abundance of experiments searching for axion dark matter (DM) via its electromagnetic coupling, there are fewer utilizing its derivative coupling to electrons and nucleons. This direct coupling generates dynamical effects through the fermion spin, and therefore spin-polarized targets are a naturally useful target. We find that spin-polarized or magnetized analogs of layered dielectric haloscopes can be powerful probes at both radio frequencies, with sensitivity to currently unexplored parameter space, and optical frequencies, with sensitivity comparable to current astrophysical bounds.",https://events.umich.edu/event/111380,"Randall Laboratory",3481,"Randall Laboratory",,"brown bag","Leinweber Center for Theoretical Physics
Department of Physics
HET Brown Bag Series
Leinweber Center for Theoretical Physics Seminars
Leinweber Center for Theoretical Physics Brown Bag Seminars"
111377-21826915,"2023-09-20 11:00:00","2023-09-20 12:00:00","Brown Bag Seminar | Geometry of Conformal Manifolds and the Inversion Formula","Bruno Balthazar (UChicago)","Lecture / Discussion","Families of conformal field theories are naturally endowed with a Riemannian geometry which is locally encoded by correlation functions of exactly marginal operators. We show that the curvature of such conformal manifolds can be computed using Euclidean and Lorentzian inversion formulae, which combine the operator content of the conformal field theory into an analytic function. Analogously, operators of fixed dimension define bundles over the conformal manifold whose curvatures can also be computed using inversion formulae. These results relate curvatures to integrated four-point correlation functions which are sensitive only to the behavior of the theory at separated points. We apply these inversion formulae to derive convergent sum rules expressing the curvature in terms of the spectrum of local operators and their three-point function coefficients. We further show that the curvature can smoothly diverge only if a conserved current appears in the spectrum, or if the theory develops a continuum. We verify our results explicitly in 2d examples.",https://events.umich.edu/event/111377,"Randall Laboratory",3481,"Randall Laboratory",,"brown bag","Leinweber Center for Theoretical Physics
Department of Physics
HET Brown Bag Series
Leinweber Center for Theoretical Physics Seminars
Leinweber Center for Theoretical Physics Brown Bag Seminars"
110719-21825353,"2023-09-27 11:00:00","2023-09-27 12:00:00","HET Brown Bag Seminar | Bootstrapping large-N confining gauge theories","Jan Albert (YITP, Stonybrook)","Lecture / Discussion","Obtaining the low-energy EFT of a given large-N confining gauge theory is in general a very difficult problem. Instead, one can proceed by carving out the space of allowed EFTs using the constraints on scattering amplitudes that follow e.g. from unitarity and crossing symmetry. In this talk I will review how to do this in the context of pion physics, with large-N QCD as our target. I will discuss what bounds this imposes on the chiral Lagrangian, and what theories saturate the bounds. I will end by discussing how a mixed system of pions and photons allows us to input symmetries and anomalies into the bootstrap, paving the way for bootstrapping large N QCD.",https://events.umich.edu/event/110719,"Randall Laboratory",3481,"Randall Laboratory",,"brown bag","Leinweber Center for Theoretical Physics
Department of Physics
HET Brown Bag Series
Leinweber Center for Theoretical Physics Seminars
Leinweber Center for Theoretical Physics Brown Bag Seminars"
112696-21829462,"2023-09-27 12:00:00","2023-09-27 13:00:00","MPSDS JPSM Seminar Series - Everything You Need to Know When Utilizing Probability Panels: Best Practices in Planning, Fielding, and Analysis","David Dutwin and Ipek Bilge - NORC at the University of Chicago","Lecture / Discussion","MPSDS SEMINAR SERIES
September 27, 2023
12:00 - 1:00 pm
IN PERSON AND VIA ZOOM
- In person, room 1070 Institute for Social Research.
- Via Zoom. The Zoom call will be locked 10 minutes after the start of the presentation.
EVERYTHING YOU NEED TO KNOW WHEN UTILIZING PROBABILITY PANELS: BEST PRACTICES IN PLANNING, FIELDING, AND ANALYSIS
Speakers: David Dutwin & Ipek Bilgen
Probability-based panel survey research is more widespread than ever, as the continuing decline in survey response rates makes cross-sectional sample surveys less and less accessible both in terms of fit for purpose data quality and cost. The attraction of probability panels for surveys is their ability to attain, dependent upon their recruiting methods, comparable response rates to cross-section polls, but at a lower cost and more expeditious execution. Panels are a unique type of survey research platform: Unlike cross-sections, panels recruit respondents specifically for future participation in surveys. In return, panelists are financially compensated, typically to join the panel in the first place, and then secondarily for each survey in which they participate.
These differences to cross-sectional surveys have a range of potential implications. How does the method and effort of recruiting impact who joins, and as a consequence what is best practice? What do panels do to retain panelists over time and which strategies are more successful than others? How much of a concern is panel conditioning, that is, the impact of persons repetitively taking surveys over time, and what are the implications for how frequently panelists should take surveys? How do panels, which exclusively request that panelists take surveys on the Internet, deal with people who do not have or are not comfortable using the Internet? What is the impact of panelist attrition and what are best efforts to replenish retired panelists? How successful are panels are executing true longitudinal surveys? And, given the additional layers of complexity, how are panel surveys properly weighted and estimated?
This seminar is meant to serve two purposes. First, it will serve as a guide for consumers of probability-based panels to understand what, in short, they are working with: What questions to ask and what features to understand about probability panels in evaluating their use for data collections, and how to best use probability-based panel data. Second, it will serve as an exploration of best practices for the practitioners of surveys: Raising issues of data quality, cost, and execution.
Learning Objectives:
1. For consumers of panel data: Understanding the features of panels with which to be knowledgeable; to know the important questions to ask panel vendors when assessing their fit for purpose of your research.
2. For researchers and practitioners: To understand the many dimensions and decision points in the building, maintenance, deployment, and delivery of multi-client panels and panel data.
Bios:
David Dutwin, PhD, is Senior Vice President for Strategic Initiatives, Business Ventures and Initiatives and Chief Scientist of AmeriSpeak at NORC at the University of Chicago. David provides scientific and programmatic thought leadership in support of NORC’s ongoing innovations. In addition to identifying new business opportunities, he lends expertise on research design conceptualization, methodological innovation, and product development. He leads the panel operations and the statistics and methods divisions of AmeriSpeak. David assists in NORC strategic vision and strategy, project acquisition and management of advance research methods. Prior research has focused on election methodology, surveying of low-incidence populations, the use of big data in survey research, and data quality in survey panels. He is a senior fellow of the Program for Opinion Research and Election Studies at the University of Pennsylvania. An avid member of the AAPOR community, David served as president from 2018-2019. He previously served on AAPOR’s Executive Council as conference chair and has served full terms on several committees. For over twenty years, he has taught courses in survey research and design, political polling, research methods, rhetorical theory, media effects, and other courses as an adjunct professor at the University of Pennsylvania, the University of Arizona, and West Chester University.
Ipek Bilgen, PhD, is a Principal Research Methodologist in the Methodology and Quantitative Social Sciences Department at NORC at the University of Chicago. Ipek is the Deputy Director of NORC’s Center for Panel Survey Sciences. Additionally, she oversees AmeriSpeak’s methodological research and innovations. As part of her role within AmeriSpeak, she also provides survey design expertise, questionnaire development and review support, and leads cognitive interview and usability testing efforts for client studies. Ipek received both her Ph.D. and M.S. from the Survey Research and Methodology (SRAM) Program at the University of Nebraska-Lincoln. She has published and co-authored articles in Journal of Official Statistics, Public Opinion Quarterly, Journal of Survey Statistics and Methodology, Survey Practice, Social Currents, Social Science Computer Review, Field Methods, Journal of Quantitative Methods, SAGE Research Methods, and Quality and Quantity on issues related to interviewing methodology, web surveys, online panels, internet sampling and recruitment approaches, nonresponse and measurement issues in surveys. In the past, she has served on AAPOR’s and MAPOR’s Executive Councils. Ipek is currently teaching at the Irving B. Harris Graduate School of Public Policy Studies at the University of Chicago and serving as Associate Editor of Public Opinion Quarterly (POQ).",https://events.umich.edu/event/112696,"Off Campus Location","Room 1070, Institute for Social Research",Virtual,,"brown bag","Michigan Program in Survey and Data Science
Institute for Social Research"
112846-21829647,"2023-10-03 12:00:00","2023-10-03 13:00:00","Brown Bag **Special Seminar** | Heisenberg's Path to Quantum Mechanics","Alexander Blum (MPI-Berlin)","Lecture / Discussion","**Special Seminar** Please note time and location
In the summer of 1925, Heisenberg wrote the paper Über quantentheoretische Umdeutung kinematischer und mechanischer Beziehungen, which laid the foundations of quantum mechanics. For a long time, this paper was considered to be inscrutable. This talk will show how one can make sense both of Heisenberg's formal manipulations and of his philosophical rhetoric, in particular by studying the letters he wrote in months leading up to his breakthrough. A particular emphasis will be placed on how different the theory that Heisenberg originally aimed to construct was from modern quantum mechanics",https://events.umich.edu/event/112846,"Randall Laboratory",3481,"Randall Laboratory",,"brown bag","Leinweber Center for Theoretical Physics
Department of Physics
HET Brown Bag Series
Leinweber Center for Theoretical Physics Seminars
Leinweber Center for Theoretical Physics Brown Bag Seminars"
111381-21826918,"2023-10-04 11:00:00","2023-10-04 12:00:00","Brown Bag Seminar | Non-perturbative de Sitter quantum gravity in low dimensions","Jordan Cotler (Harvard)","Lecture / Discussion","Little is known about non-perturbative quantum gravity in de Sitter spacetimes. As a useful low-dimensional model, we consider de Sitter Jackiw-Teitelboim (dS JT) gravity and solve it non-perturbatively in the genus expansion. This amounts to the first non-perturbatively solvable model of de Sitter cosmology. We find that dS JT gravity has an effective string coupling which is pure imaginary, rendering the S-matrix genus expansion Borel resummable. We further establish that dS JT gravity is dual to a formal matrix integral with a negative number of degrees of freedom. More broadly, our analysis unveils new ingredients in the de Sitter holographic dictionary, which may be applicable in more general contexts.",https://events.umich.edu/event/111381,"Randall Laboratory",3481,"Randall Laboratory",,"brown bag","Leinweber Center for Theoretical Physics
Department of Physics
HET Brown Bag Series
Leinweber Center for Theoretical Physics Seminars
Leinweber Center for Theoretical Physics Brown Bag Seminars"
113114-21830116,"2023-10-04 13:00:00","2023-10-04 14:00:00","MPSDS JPSM Seminar Series - Using Partially Synthetic Frames to Evaluate Alternative Sample Designs for Estimating a Rare Business Characteristic","Katherine Jenny Thompson - U.S. Census Bureau","Lecture / Discussion","MPSDS JPSM Seminar Series
October 4, 2023
12:00 - 1:00 pm EDT
In person, room 1070 Institute for Social Research, and via Zoom. The Zoom call will be locked 10 minutes after the start of the presentation.
Using Partially Synthetic Frames to Evaluate Alternative Sample Designs for Estimating a Rare Business Characteristic
Katherine Jenny Thompson, U.S. Census Bureau
Hang Joon Kim (University of Cincinnati)
Stephen Kaputa (U.S. Census Bureau)
In the “traditional'” finite population sampling framework, the sample designer has a complete list (frame) of eligible units with classification information and auxiliary variables related to surveyed characteristics. In our setting, the frame auxiliary variables are weakly related to the survey characteristic, which is not present for most units. Hence, using frame auxiliary variables to assess survey design efficacy can be misleading. Instead, we propose generating multiple partially synthetic frames, modeling characteristic values for each unit on the frame, then drawing repeated samples from each synthetic frame using the candidate sample design(s) to assess finite sample performance for each design within and between the synthetic frames. Focusing on establishment survey data, we illustrate our proposed approach on a subset of industries surveyed annually by the Business Enterprise Research and Development Survey.
Katherine Jenny Thompson is the Senior Mathematical Statistician in the Economic Directorate of the Census Bureau. Jenny holds a masters of science degree in Applied Statistics from the George Washington University and an bachelor or arts degree in Mathematics from Oberlin College. She is an American Statistical Association (ASA) Fellow, an elected member of the International Statistics Institute, and the Vice President Elect of the ASA. She is the Survey Statistics Editor-in-Chief of the Journal of Survey Statistics and Methodology and an Associate Editor for the Journal of Official Statistics. She has published papers on a variety of topics related to complex surveys in several journals, including the Journal of Official Statistics, Journal of the Royal Statistical Society (Series A), Survey Methodology, Annals of Applied Statistics, International Statistical Review, Journal of Survey Sampling and Methodology, and Public Opinion Quarterly.",https://events.umich.edu/event/113114,"Off Campus Location","Room 1070, Institute for Social Research",Virtual,,"brown bag","Michigan Program in Survey and Data Science
Institute for Social Research"
111382-21826919,"2023-10-25 11:00:00","2023-10-25 12:00:00","Brown Bag Seminar |","Hofie Hannisdottir","Lecture / Discussion",TBD,https://events.umich.edu/event/111382,"Randall Laboratory",3481,"Randall Laboratory",,"brown bag","Leinweber Center for Theoretical Physics
Department of Physics
HET Brown Bag Series
Leinweber Center for Theoretical Physics Seminars
Leinweber Center for Theoretical Physics Brown Bag Seminars"
111383-21826920,"2023-11-08 11:00:00","2023-11-08 12:00:00","Brown Bag Seminar |","Sergio Hernandez-Cuenca (MIT)","Lecture / Discussion",TBD,https://events.umich.edu/event/111383,"Randall Laboratory",3481,"Randall Laboratory",,"brown bag","Leinweber Center for Theoretical Physics
Department of Physics
HET Brown Bag Series
Leinweber Center for Theoretical Physics Seminars
Leinweber Center for Theoretical Physics Brown Bag Seminars"
111384-21826921,"2023-11-15 11:00:00","2023-11-15 12:00:00","Brown Bag Seminar |","Matthew Heydeman (Harvard)","Lecture / Discussion",TBD,https://events.umich.edu/event/111384,"Randall Laboratory",3481,"Randall Laboratory",,"brown bag","Leinweber Center for Theoretical Physics
Department of Physics
HET Brown Bag Series
Leinweber Center for Theoretical Physics Seminars
Leinweber Center for Theoretical Physics Brown Bag Seminars"
111385-21826922,"2023-11-29 11:00:00","2023-11-29 12:00:00","Brown Bag Seminar |","Hongwan Liu (UChicago/Fermilab)","Lecture / Discussion",TBD,https://events.umich.edu/event/111385,"Randall Laboratory",3481,"Randall Laboratory",,"brown bag","Leinweber Center for Theoretical Physics
Department of Physics
HET Brown Bag Series
Leinweber Center for Theoretical Physics Seminars
Leinweber Center for Theoretical Physics Brown Bag Seminars"
111386-21826923,"2023-12-06 11:00:00","2023-12-06 12:00:00","Brown Bag Seminar |","Tannar Trickle (FNAL)","Lecture / Discussion",TBD,https://events.umich.edu/event/111386,"Randall Laboratory",3481,"Randall Laboratory",,"brown bag","Leinweber Center for Theoretical Physics
Department of Physics
HET Brown Bag Series
Leinweber Center for Theoretical Physics Seminars
Leinweber Center for Theoretical Physics Brown Bag Seminars"
108977-21820671,"2024-01-17 12:00:00","2024-01-17 13:00:00","MPSDS JPSM Seminar Series - Using Synergies Between Survey Statistics and Causal Inference to Improve Transportability of Clinical Trials","Michael Elliott - Survey Methodology Program - Michigan Program in Survey and Data Science","Lecture / Discussion","MPSDS Seminar Series
January 17, 2024
12:00 - 1:00 pm
In person, room 1070 Institute for Social Research, and via Zoom. The Zoom call will be locked 10 minutes after the start of the presentation.
Using Synergies Between Survey Statistics and Causal Inference to Improve Transportability of Clinical Trials
Medical researchers have understood for many years that treatment effect estimates obtained from a randomized clinical trial (RCT) -- termed efficacy'' -- can differ from those obtained in a general population -- termed effectiveness''. Only in the past decade has extensive work begun in the statistical literature to bridge this gap using formal quantitative methods. As noted by Rod Little in a letter to the editor in the New Yorker ...randomization in randomized clinical trials concerns the allocation of the treatment, not the selection of individuals for the study. The latter can have an important impact on the average size of a treatment effect,'' with RCT samples often designed, sometimes explicitly, to be more likely to include individuals for whom the treatment may be more effective.
This issue has been various termed generalizability'' or transportability."" Why do we care about transportability? In RCTs we are in the happy situation were treatment assignment is randomized, so confounding due to either observed or unobserved (pre-treatment) covariates is not an issue. But while randomization of treatment eliminates the effect of unobserved confounders, at least net of non-compliance, it does not eliminate the effect of unobserved effect modifiers, which can impact the causal effect of treatment in a population that differs from the RCT sample population. The impact of these interactions on the marginal effect of treatment thus can differ between the RCT population and the final population of interest.
Concurrent with research into transportability has been research into making population inference from non-probability samples. There is a close overlap between these two approaches, particularly with respect to the non-probability inference methods that rely on information from a relevant probability sample of the target population to reduce selection bias effects. When there are relevant censuses or probability samples of the target patient population of interest, these methods can be adapted to transport information from the RCT to the patient population. Because the RCT setting focuses on causal inference, this adaptation involves extensions to estimate counterfactuals. Thus approaches that treat population inference as a missing data problem are a natural fit to connect these two strands of methodological innovation.
In particular, we propose to extend a pseudo-weighting'' methodology from other non-probability settings to a doubly robust'' estimator that treats sampling probabilities or weights as regression covariates to achieve consistent estimation of population quantities. We explore our proposed approach and compare with some standard existing methods in a simulation study to assess the effectiveness of the approach under differing degrees of selection bias and model misspecification, and compare it with results obtained using the RT data only and with existing methods that use inverse probability weights. We apply it to a study of pulmonary artery catheterization in critically ill patients where we believe differences between the trial sample and the larger population might impact overall estimates of treatment effects.",https://events.umich.edu/event/108977,"Off Campus Location","Room 1070, Institute for Social Research",Virtual,,"brown bag","Michigan Program in Survey and Data Science
Institute for Social Research"