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X-WR-CALDESC:Events for CREST
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DTSTART:20190331T010000
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DTSTART:20191027T010000
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DTSTART;TZID=Europe/Paris:20190624T103000
DTEND;TZID=Europe/Paris:20190624T114500
DTSTAMP:20260821T090624
CREATED:20190531T111455Z
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SUMMARY:Zheng Tracy KE (Harvard University) - "Optimal Adaptivity of Signed-Polygon Statistics for Network Testing"
DESCRIPTION:\nThe Statistical Seminar: \nTime: 10:30 am – 11:45 am\nDate: 24th of June 2019\nPlace: Room 3105.\nZheng Tracy KE (Harvard University) – “Optimal Adaptivity of Signed-Polygon Statistics for Network Testing“ \nAbstract:Given a symmetric social network\, we are interested in testing whether it has only one community or multiple communities. The desired tests should (a) accommodate severe degree heterogeneity\, (b) accommodate mixed-memberships\, (c) have a tractable null distribution\, and (d) adapt automatically to different levels of sparsity\, and achieve the optimal phase diagram. How to find such a test is a challenging problem. \nWe propose the Signed Polygon as a class of new tests. Fixing m ≥ 3\, for each m-gon in the network\, define a score using the centered adjacency matrix. The sum of such scores is then the m-th order Signed Polygon statistic. The Signed Triangle (SgnT) and the Signed Quadrilateral (SgnQ) are special examples of the Signed Polygon. We show that both the SgnT and SgnQ tests satisfy (a)-(d)\, and especially\, they work well for both very sparse and less sparse networks. Our proposed tests compare favorably with the existing tests. For example\, the EZ and GC tests behave unsatisfactorily in the less sparse case and do not achieve the optimal phase diagram. Also\, many existing tests do not allow for severe heterogeneity or mixed-memberships\, and they behave unsatisfactorily in our settings. \nThe analysis of the SgnT and SgnQ tests is delicate and tedious\, and the main reason is that we need a unified proof that covers a wide range of sparsity levels and a wide range of degree heterogeneity. For lower bound theory\, we use a phase transition framework\, which includes the standard minimax argument\, but is more informative. The proof uses classical theorems on matrix scaling.\n(Joint work with Jiashun Jin and Shengming Luo. arXiv preprint: https://arxiv.org/abs/1904.09532)\nOrganizers:\nCristina BUTUCEA\, Alexandre TSYBAKOV\, Julie JOSSE\, Eric MOULINES\, Mathieu ROSENBAUM\nSponsors:\nCREST-CMAP\n \n\n
URL:https://crest.science/event/zheng-tracy-ke/
CATEGORIES:Statistics
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DTSTART;TZID=Europe/Helsinki:20190624T110000
DTEND;TZID=Europe/Helsinki:20190624T120000
DTSTAMP:20260821T090624
CREATED:20191023T115607Z
LAST-MODIFIED:20191023T115607Z
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SUMMARY:Morgane Guignard (CREST) - "How Innovation Affects Bargaining and Profit Sharing ?"
DESCRIPTION:CREST Internal Seminar in Microeconomics :  \n\nTime: 11:00 am – 12:00 pm\nDate: 24th June 2019\nPlace: Room 3105.\nMorgane Guignard – “How Innovation Affects Bargaining and Profit Sharing ?” \nAbstract: We study the impact of innovation on the bargaining power of firms vis-à-vis trading partners.\nTo do so\, we use a structural econometric model of demand that accounts for consumer\nadoption of innovations over time. We develop a supply model of bilateral bargaining between\nmanufacturers and retailers and identify how innovation impacts the bargaining position and\nprofit sharing. Using data on margarine purchasers in France from 2001 to 2009\, we focus on\nthe introduction of two new products with health attributes (anticholesterol and Omega 3 margarines).\nFirms strategically introduce these new products to take advantages of the increasing\ntrend in preferences for healthy products as an attribute of differentiation over standard\nmargarine. Preliminary results suggest that the introduction of innovation allows suppliers to\nobtain a higher share of profits and increase their bargaining ability with respect to retailers. \n\n\nOrganizers:\nAlexis Larousse (CREST)\nSponsors:\nCREST\nLunch registration:\nno registration needed\n\n  \n
URL:https://crest.science/event/morgane-guignard-how-innovation-affects-bargaining-and-profit-sharing-evidence-from-the-margarine-market/
LOCATION:3105
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DTSTART;TZID=Europe/Paris:20190624T140000
DTEND;TZID=Europe/Paris:20190624T151500
DTSTAMP:20260821T090624
CREATED:20190531T110849Z
LAST-MODIFIED:20190531T110849Z
UID:12272-1561384800-1561389300@crest.science
SUMMARY:Jonas PETERS (University of Copenhagen) - "The Impossibility of Conditional Independence Testing and Causality in Dynamical Systems"
DESCRIPTION:\nThe Statistical Seminar: Every Monday at 2:00 pm.\nTime: 2:00 pm – 3:15 pm\nDate: 24th of June 2019\nPlace: Room 3001.\nJonas PETERS (University of Copenhagen) – “The Impossibility of Conditional Independence Testing and Causality in Dynamical Systems“ \nAbstract: In this talk\, we (1) discuss in which sense conditional independence testing for continuous random variables is an unsolvable statistical problem. (2) We also introduce CausalKinetiX\, a framework that aims at learning the underlying structure in dynamical systems by trading off invariance and predictability. The talk contains joint work with Rajen Shah\, Niklas Pfister\, and Stefan Bauer. No prior knowledge about causality is required. \nOrganizers:\nCristina BUTUCEA\, Alexandre TSYBAKOV\, Julie JOSSE\, Eric MOULINES\, Mathieu ROSENBAUM\nSponsors:\nCREST-CMAP\n \n\n
URL:https://crest.science/event/jonas-peters/
CATEGORIES:Statistics
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