Random

random@lists.dm.unipi.it

23 participants
5095 discussions

Biometrical Journal, Special Issue on "Models for continuous data with a spike at zero"
by Pierpaolo Brutti 16 Dec '13

16 Dec '13

...ricevo e inoltro... ### APOLOGIES FOR CROSS_POSTING #### The Biometrical Journal is a leading journal in biometry. It is calling for papers for a special issue on "Models for continuous data with a spike at zero". Zero-inflation models for count data have a long history and a huge amount of published research exists to the topic. In fact, the Biometrical Journal has contributed numerous papers to this area since zero-inflated count data are a prominent problem in the life-sciences. See, for example, the September 2013 issue of the Biometrical Journal. In this call, we would like to draw the attention of the research community to another prominent problem in the life sciences: continuous data with a spike at zero. The extra-zeros can arise out of many reasons and it is not necessarily clear how they could be handled. A frequent problem is the occurrence of data below a limit of detection (LOD). In these cases, it might be reasonable to treat them as left-censored. A further modeling alternative could be that of employing so called two-step models, where at the first stage a binary variable describes whether or not the observed value is above the limit of detection while, at the second stage, a continuous variable is used to describe positive measurements. In other cases, it is less clear how to approach the problem. For example, consider the consumption of alcohol measured on a continuous scale. Then, there is a spike at zero representing the non-drinkers. The zeros are neither left-censored nor interval-censored. Here, there are at least two problems involved. For one, the quantity of interest is bounded below, and for two, the zeros create a single mass distribution. A further empirical application where extra-zeros may arise is when modeling length of stay in hospital admissions. This is frequently modeled following a count data approach, although the underlying quantity is continuous. In length-of-stay situations, day surgery patients may be classified as having a null length of stay but, for administrative purposes, it could be necessary for them to be considered together with in-hospital patients whose length of stay is positive. Hence, we have a continuous quantity bounded below by zero and a spike at zero. In a regression context, we also think that these spikes could occur on the left-hand side of a regression equation as well as on the right-hand side, i.e. for the dependent (outcome) and the independent (predictor) variables With this call for submissions we are looking for novel contributions presenting • authentic continuous data with excess-zeros • novel statistical approaches to handle these issues. • up-to-date case studies which address the above issues and are of interest for the biometric community. . Authors, who are not sure whether their problems and ideas fall under the call or not, may approach the Editors with an initial draft of the paper. All submitted papers under this call will undergo the standard review process of the journal. The deadline for papers for this call is May 31, 2014. The special issue is handled through the website of the Biometrical Journal and is handled as any other paper submitted to the journal except that the editing and the review process is handled by the Special Issue Editors Dankmar Böhning and Marco Alfó. Please submit your manuscript at is http://mc.manuscriptcentral.com/biomj To submit to the special issue login at MC (manuscript central), indicate at Step 1 that the submission is to a special issue and at Step 4 of the submission process enter "ZERO I" in the Special Issue Information field. Submitted manuscripts should comply with the instructions for authors of Biometrical Journal which you find on the Biometrical Journal homepage using the link to the Author Guidelines.

1 0

Fwd: Fwd: [dynlist]--CRM-PISA Junior Visiting Program (fwd)
by Tiziano Vargiolu 13 Dec '13

13 Dec '13

---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.

1 0

Re: [Random] probability hiring (fwd)
by Tiziano Vargiolu 13 Dec '13

13 Dec '13

---------- Forwarded message ---------- Date: Thu, 12 Dec 2013 18:58:19 -0500 From: Alberto Bressan <bressan(a)math.psu.edu> ============================================================================== Subject to availability of funding, the Penn State Mathematics Department will seek to fill openings for S. Chowla Research Assistant Professors and for tenure and tenure track faculty positions. Tenure or Tenure Track Faculty Position Candidates from all areas of mathematics will be considered. There may be up to three positions in the area of Probability. A Ph.D. degree or its equivalent is required. Online application via www.mathjobs.org is strongly preferred. Review of applications will begin November 15, 2013 and will continue until positions are filled. Required application materials include: --Online application --At least three reference letters, one of which should address in detail the candidate's abilities as a teacher --Curriculum Vitae --Publication List --Research Statement --Teaching Statement Persons who are unable to apply using the mathjobs.org website or who do not wish to do so may send application materials to: Search Committee Department of Mathematics Penn State University 107 McAllister Building University Park, PA 16802 We encourage applications from individuals of diverse backgrounds. Penn State is committed to affirmative action, equal opportunity, and the diversity of its workforce. =============================================================================

1 0

Seminario KLEIJN
by Matteo Ruggiero 13 Dec '13

13 Dec '13

**************************************************************** STATISTICS SEMINARS - COLLEGIO CARLO ALBERTO **************************************************************** Venerdi' 20 dicembre 2013 alle ore 12:00, presso la sala rossa del Collegio Carlo Alberto, Moncalieri (TO), si terra' il seguente seminario: Bas KLEIJN (University of Amsterdam) TESTABILITY AND CONSISTENCY Abstract: Bayesian consistency theorems come in (at least) three distinct types, e.g. Doob's prior-almost-sure consistency on Polish spaces, Schwartz's Hellinger consistency with KL-priors and the `tailfree' weak consistency of Dirichlet posteriors. In this talk we ask the question how these notions of convergence are related and argue that one characterises them most conveniently using test sequences. We investigate the differences between uniform, point-wise and almost-sure testing, prove Doob-type posterior consistency theorems in various model topologies and consider hypothesis testing problems like Cover's rational mean problem (Cover, 1973). To achieve frequentist posterior consistency, we combine almost-sure tests with a prior condition that generalises Schwartz's KL-condition and is conjectured also to accomodate `tailfree' behaviour like that of Dirichlet posteriors. Tutti gli interessati sono invitati a partecipare. Il seminario e' organizzato dalla "de Castro" Statistics Initiative (http://www.carloalberto.org/stats) in collaborazione con il Collegio Carlo Alberto. Cordiali saluti, Matteo Ruggiero --------- Matteo Ruggiero University of Torino & Collegio Carlo Alberto http://web.econ.unito.it/ruggiero

1 0

Modifica orario- Seminario F. Martinelli
by alessandra bianchi 10 Dec '13

10 Dec '13

Martedi' 17 dicembre 2013 alle ore 16 presso l'aula 1BC50 del Dipartimento di Matematica di Padova il Prof. Fabio Martinelli (Dip. di Matematica, Universita' di Roma Tre) terra' il seguente seminario Title: Time scales separation and dynamical heterogeneities in the East model. Abstract: The East model is a finite linear Markov chain of 0-1 spins, evolving according to a very simple rule: i) with rate 1 and independently for each vertex, a new value 1/0 is proposed with probability 1-q and q respectively; ii) the proposed value is accepted iff the spin immediately to the left is 0. The model and its generalizations play an important role as models of the dynamics of real glasses. The parameter q, which turns out to be the density of the zeros (the facilitating spins) in the stationary measure, is assumed to be very small. In the physical literature this setting corresponds to a low temperature case. We will examine the problem of dynamic heterogeneity, i.e. non-trivial spatio-temporal fluctuations of the local relaxation to equilibrium. A key result will be a very precise computation of the relaxation time of the chain as a function of q and of its length, which uses induction on length scales on one hand and a novel algorithmic lower bound on the other. Our findings reject non rigorous approaches based on numerical simulations. We will conclude with a conjecture due to D. Aldous and P. Diaconis about the scaling limit of the East chain as q-->0. Joint work with A. Faggionato and P. Chleboun -- Alessandra Bianchi Dip. di Matematica Pura e Applicata Università di Padova Via Trieste, 63 - 35121 Padova, Italy phone: +39 049 827 14 06 fax: +39 049 827 14 28 e-mail: bianchi(a)math.unipd.it http://www.math.unipd.it/~bianchi/

1 0

Post-Doc position in Modena
by Cristian Giardina 10 Dec '13

10 Dec '13

*---------------------------------------------------------* *1 Post-doctoral fellowship for 2014-2015* Announcement: The University of Modena and Reggio Emilia has an open call for 1 Post-doctoral position (1+1 year) funded by the Italian Ministry of Education and Research in the framework of the FIRB project “Stochastic processes in interacting particle systems: duality, metastability and applications” (www.stochastics.unimore.it/firb). Short description: The candidate is expected to work on interacting particle systems, with emphasis on non-equilibrium processes and population dynamics, including their algorithmic aspects. Specific research topics include Markov stochastic processes (both diffusions and jump processes) and large deviations theory. The aim is to develop probabilistic tools, such as duality theory, for the analysis of stochastic processes in the context of mathematical population genetics and its applications to importance sampling algorithms with cloning. Job requirements: - Early stage researcher with background in mathematical physics, probability, statistical mechanics; - PhD in Mathematics or PhD in Physics (obtained or soon to be obtained); - shaped scientific personality, independent thinker; - author of recent publications on peer-reviewed international journals; - strong theoretical background but also an interest in application-oriented research. Salary: 27.429 euros (gross) per year. Application: The deadline for application is January 7th, 2014 and the position has to start before February 28th, 2014. Interested candidates can contact Prof. Cristian Giardina’ (cristian.giardina(a)unimore.it, +39 338 6115896). They are welcome to ask questions when filling in the application form. Please also include in your application the contact information of two researchers who are acquainted with your previous work. The call (english version) is available at: http://www.ufficioselezioneassunzione.unimore.it/site/home/assegni-di-ricer… The call (italian version) is available at: http://www.ufficioselezioneassunzione.unimore.it/site/home/assegni-di-ricer…

1 0

Seminario di Probabilità - Università di Padova
by alessandra bianchi 09 Dec '13

09 Dec '13

Ho il piacere di invitarvi al seguente seminario che si terrà martedì 17 dicembre 2013 alle ore 15 nell'aula 1BC50 del Dipartimento di Matematica di Padova. Speaker: Prof. Fabio Martinelli , Dip. di Matematica, Università di Roma Tre Title: Time scales separation and dynamical heterogeneities in the East model. Abstract: The East model is a finite linear Markov chain of 0-1 spins, evolving according to a very simple rule: i) with rate 1 and independently for each vertex, a new value 1/0 is proposed with probability 1-q and q respectively; ii) the proposed value is accepted iff the spin immediately to the left is 0. The model and its generalizations play an important role as models of the dynamics of real glasses. The parameter q, which turns out to be the density of the zeros (the facilitating spins) in the stationary measure, is assumed to be very small. In the physical literature this setting corresponds to a low temperature case. We will examine the problem of dynamic heterogeneity, i.e. non-trivial spatio-temporal fluctuations of the local relaxation to equilibrium. A key result will be a very precise computation of the relaxation time of the chain as a function of q and of its length, which uses induction on length scales on one hand and a novel algorithmic lower bound on the other. Our findings reject non rigorous approaches based on numerical simulations. We will conclude with a conjecture due to D. Aldous and P. Diaconis about the scaling limit of the East chain as q-->0. Joint work with A. Faggionato and P. Chleboun -- Alessandra Bianchi Dip. di Matematica Pura e Applicata Università di Padova Via Trieste, 63 - 35121 Padova, Italy phone: +39 049 827 14 06 fax: +39 049 827 14 28 e-mail: bianchi(a)math.unipd.it http://www.math.unipd.it/~bianchi/

1 0

Avviso di seminario :: DiSerio@DSS (Scienze Statistiche, Sapienza)
by Pierpaolo Brutti 09 Dec '13

09 Dec '13

----------------------------------------------------------------------------- A v v i s o d i S e m i n a r i o ----------------------------------------------------------------------------- Venerdì 13 Dicembre, ore 11am ----------------------------------------------------------------------------- Stanza 34 Dipartimento di Scienze Statistiche Sapienza Università di Roma CLELIA DI SERIO (Centro Universitario di Statistica per le Scienze Biomediche, Università Vita-Salute San Raffaele) terrà un seminario dal titolo INVESTIGATING TUMOR DORMANCY WITH FRAILTY tutti gli interessati sono invitati a partecipare. ----------------------------------------------------------------------------- Maggiori informazioni sui seminari presso il DSS sono consultabili a quest'indirizzo: http://goo.gl/Y6OQYm Saluti Pierpaolo Brutti - Fulvio De Santis --- Summary A non-negligible percentage of cancer patients relapse after years or decades after surgical removal of the primary tumor. This phenomenon is not following a random memory-less process and its timing is reflected in hazard rates, with respect to both relapse and mortality, showing multimodal shapes. From a biomedical perspective, such a behavior may be explained by tumor dormancy, i.e. for some patients microscopic tumor foci may remain asymptomatic for a prolonged time interval and, when they escape from dormancy, micrometastatic growth results in a clinical disease appearance. The activation of the growth phase at different metastatic states would explain the occurrence of metastatic recurrences and mortality at different times (multimodal hazard). We place this phenomenon in the framework of survival frailty models. We propose a new statistical approach which models the risk function by considering possible effects of Gamma frailty and compound Poisson fraity in acting on components of the hazard function. Thus, the individual hazard rate is the product of a random frailty variable and the sum of basic hazard rates. The basic hazard rates correspond to micrometastatic developments starting from different initial states. The frailty variable represents the heterogeneity between patients with respect to relapse, which might be related to unknown mechanisms that regulate tumor dormancy. The model is applied to analyze the mortality of patients in a large breast cancer dataset. We show how this framework can appropriately model the tumor dormancy phenomenon and possibly improve the understanding of this biological process.

1 0

Statistica Open Data e Società - Milano, 13 dicembre 2013
by Consonni Guido 06 Dec '13

06 Dec '13

Al termine dell'iniziativa "Statistica Open Data e Società", concorso a premi promosso dal Dipartimento di Scienze statistiche dell'Università Cattolica del Sacro Cuore in collaborazione con il Comune di Milano, nell'ambito delle celebrazioni per l'Anno Internazionale della Statistica, http://convegni.unicatt.it/meetings_2471.html<http://convegni.unicatt.it/meetings_2471.html,>, <http://convegni.unicatt.it/meetings_2471.htmlsi> si segnala l'evento "Come Open Data e Statistica possono aiutarci a conoscere e migliorare la società", in programma per venerdì 13 dicembre alle ore 18.00 presso l'Acquario Civico di Milano, nel corso del quale saranno premiati i vincitori. La partecipazione è libera, ma per motivi organizzativi si prega di segnalarla inviando una mail a dip.scienzestatistiche(a)unicatt.it<mailto:dip.scienzestatistiche@unicatt.it>. Di seguito il programma e altre informazioni. Venerdì 13 dicembre 2013, ore 18:00, Acquario Civico, Viale Gadio, 2 - Milano Saluti e introduzione: Cristina TAJANI Assessore alle Politiche per il lavoro, Sviluppo economico, Università e ricerca Guido CONSONNI Presidente della Giuria "Statistica, Open Data e Società", Università Cattolica del Sacro Cuore Alessandro ROSINA Direttore del Laboratorio di Statistica applicata alla decisioni economico-aziendali, Università Cattolica del Sacro Cuore Interventi: Nicola TORELLI Presidente della Società Italiana di Statistica, Marco ALFIERI Direttore de Linkiesta Presentazione dei prodotti vincitori del Contest "Statistica, Open Data e Società" Consegna dei premi da parte di Nunatac e Synergia Conclusioni: Cristina TAJANI Assessore alle Politiche per il lavoro, Sviluppo economico, Università e ricerca Brindisi finale

1 0

Post-doc a Lione
by Francesco Caravenna 05 Dec '13

05 Dec '13

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% Post-doc positions - Mathematics and Computer Science in Lyon (labex MILYON) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% See: http://milyon.universite-lyon.fr/offres-de-post-docs/2-post-doctoral-positi… Offer: MILYON (the Laboratoire d'Excellence "Mathématiques et Informatique à Lyon") offers four post-doctoral positions in mathematics and two in computer science for the academic year 2014-2015, to be held at the Unité de Mathématiques Pures et Appliquées or at the Laboratoire de l'Informatique du Parallélisme (École Normale Supérieure de Lyon), or at the Institut Camille Jordan (Université Claude Bernard Lyon 1). These are research-only appointments (without teaching). They are typically for two years, with possible renewal for a third year subject to review. The salary will be 2100 euros per month, with benefits including health insurance and social coverage. Funds will also be provided for traveling and inviting collaborators. Full description: More information can be found on the website of MILYON which contains links to the above three departments. It is requested to contact the colleagues in Lyon who are closest to your specialty. Eligibility: For holders of a Ph.D in mathematics or computer science obtained before October 1st, 2014. Deadline: Applications must be complete (including all reference letters) by: Wednesday, January 15th, 2014, at 17:00 (Lyon local time). How to apply? Applications must be submitted via the online form: http://math.univ-lyon1.fr/limesurvey/index.php?sid=32222&lang=en Requested items: Requested items: - a curriculum vitae; - a list of publications; - a scientific project (around two pages) specifying members of MILYON with whom you plan to interact primarily; - a short letter by a local mentor from Labex MILYON; - two detailed recommendation letters by scientists, not members of MILYON (one of them can be the thesis adviser). Contact: Administrative contact: Carine Sevestre <sevestre(a)math.univ-lyon1.fr> Only for scientific matters: Francis FILBET <filbet(a)math.univ-lyon1.fr>

1 0

Jump to page:

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

Random