Fabrizio Leisen

ORCID: 0000-0002-2460-6176
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Research Areas
  • Bayesian Methods and Mixture Models
  • Statistical Methods and Inference
  • Statistical Methods and Bayesian Inference
  • Financial Risk and Volatility Modeling
  • Markov Chains and Monte Carlo Methods
  • Stochastic processes and statistical mechanics
  • Probability and Risk Models
  • Statistical Distribution Estimation and Applications
  • Bayesian Modeling and Causal Inference
  • Random Matrices and Applications
  • Stochastic processes and financial applications
  • Insurance, Mortality, Demography, Risk Management
  • Theoretical and Computational Physics
  • Genetic Associations and Epidemiology
  • Mathematical Dynamics and Fractals
  • Gaussian Processes and Bayesian Inference
  • Statistical Mechanics and Entropy
  • Advanced Statistical Methods and Models
  • Complex Systems and Time Series Analysis
  • Diffusion and Search Dynamics
  • Monetary Policy and Economic Impact
  • Control Systems and Identification
  • Analytic Number Theory Research
  • Machine Learning and Algorithms
  • Statistical Methods in Clinical Trials

King's College London
2024

University of Nottingham
2020-2023

University of Kent
2013-2020

Ca' Foscari University of Venice
2016

Universidad Carlos III de Madrid
2010-2013

University of Pavia
2013

University of Warwick
2013

Instituto Superior de Ciências Económicas e Empresariais
2010-2011

University of Modena and Reggio Emilia
2010

Universidad de Navarra
2010

Summary A new class of dependent random measures which we call compound is proposed and the use normalized versions these as priors in Bayesian non-parametric mixture models considered. Their tractability allows properties both to be derived. In particular, show how can constructed with gamma, σ-stable generalized gamma process marginals. We also derive several forms Laplace exponent characterize dependence through Lévy copula correlation function. An augmented Pólya urn scheme sampler a...

10.1111/rssb.12176 article EN cc-by Journal of the Royal Statistical Society Series B (Statistical Methodology) 2016-04-14

Many popular Bayesian nonparametric priors can be characterized in terms of exchangeable species sampling sequences. However, some applications, exchangeability may not appropriate. We introduce a novel and probabilistically coherent family non-exchangeable sequences by tractable predictive probability function with weights driven sequence independent Beta random variables. compare their theoretical clustering properties those the Dirichlet Process two parameters Poisson-Dirichlet process....

10.1080/01621459.2014.950735 article EN Journal of the American Statistical Association 2014-08-15

We are living in the big data era, as current technologies and networks allow for easy routine collection of sets different disciplines. Bayesian Statistics offers a flexible modeling approach which is attractive describing complexity these datasets. These models often exhibit likelihood function intractable due to large sample size, high number parameters, or functional complexity. Approximate Computational (ABC) methods provides likelihood-free performing statistical inferences with...

10.1214/18-ss120 article EN Statistics Surveys 2018-01-01

In this paper the theory of species sampling sequences is linked to conditionally identically distributed in order enlarge set which are mathematically tractable. The conditional identity distribution (see Berti, Pratelli and Rigo (2004)) a new type dependence for random variables, generalizes well-known notion exchangeability. class sequences, called generalized , defined condition have given. Moreover, two types sequence that introduced studied: Poisson-Dirichlet Ottawa . Some examples discussed.

10.1239/aap/1275055237 article EN Advances in Applied Probability 2010-05-28

10.1016/j.jmva.2010.10.008 article EN Journal of Multivariate Analysis 2010-10-17

We deal with Bayesian model selection for beta autoregressive processes. discuss the choice of parameter and priors possible restrictions suggest a Reversible Jump Markov-Chain Monte Carlo (RJMCMC) procedure based on Metropolis-Hastings within Gibbs algorithm.

10.1214/12-ba713 article EN Bayesian Analysis 2012-05-24

Monte Carlo methods have become essential tools to solve complex Bayesian inference problems in different fields, such as computational statistics, machine learning, and statistical signal processing. In this work, we introduce a novel class of adaptive methods, called independent sticky Markov Chain (MCMC) algorithms, sample efficiently from any bounded target probability density function (pdf). The new algorithms employs non-parametric proposal densities, which closer the number iterations...

10.1186/s13634-017-0524-6 article EN cc-by EURASIP Journal on Advances in Signal Processing 2018-01-11

Summary There is an increasing amount of literature focused on Bayesian computational methods to address problems with intractable likelihood. One approach a set algorithms known as Approximate Computational (ABC) methods. the these that their performance depends appropriate choice summary statistics, distance measure and tolerance level. To circumvent this problem, alternative method based empirical likelihood has been introduced. This can be easily implemented when constraints, related...

10.1111/anzs.12156 article EN Australian & New Zealand Journal of Statistics 2016-06-01

Summary Several studies on heritability in twins aim at understanding the different contribution of environmental and genetic factors to specific traits. Considering national merit twin study, our purpose is analyse correctly influence socio-economic status relationship between twins’ cognitive abilities. Our methodology based conditional copulas, which enable us model effect a covariate driving strength dependence main variables. We propose flexible Bayesian non-parametric approach for...

10.1111/rssc.12237 article EN cc-by-nc Journal of the Royal Statistical Society Series C (Applied Statistics) 2017-08-08

Let X=(X1,X2,…) be a sequence of random variables with values in standard space (S,B). Suppose X1∼νandP(Xn+1∈⋅∣X1,…,Xn)=θν(⋅)+ ∑i=1nK(Xi)(⋅) n+θa.s. where θ>0 is constant, ν probability measure on B, and K B. Then, X exchangeable whenever regular conditional distribution for given any sub-σ-field Under this assumption, enjoys all the main properties classical Dirichlet sequences, including Sethuraman's representation, conjugacy property, convergence total variation predictive distributions....

10.3150/22-bej1500 article EN Bernoulli 2023-02-20

Random probability vectors are of great interest especially in view their application to statistical inference. Indeed, they can be used for identifying the de Finetti mixing measure representation law a partially exchangeable array random elements taking values separable and complete metric space. In this paper we describe construction vector Dirichlet processes based on normalization an completely measures that jointly infinitely divisible. After deducing form multivariate Laplace exponent...

10.1214/12-ejs764 article EN cc-by Electronic Journal of Statistics 2013-01-01

We build on the derivative pricing calibration literature, and propose a more general model for implied risk neutral densities. Our allows joint of set densities at different maturities dates through Bayesian dynamic Beta Markov Random Field. approach possible time dependence between with same maturity, across point in time. This to density problem encompasses flexibility, parameter parsimony, and, importantly, information pooling proposed methodology can be naturally extended other areas...

10.1214/15-ba960si article EN Bayesian Analysis 2015-06-22

AbstractIn the big data era there is a growing need to model main features of large and non-trivial sets. This paper proposes Bayesian nonparametric prior for modelling situations where are divided into different units with densities, allowing information pooling across groups. Leisen Lijoi [(2011), 'Vectors Poisson–Dirichlet processes', J. Multivariate Anal., 102, 482–495] introduced bivariate vector random probability measures marginals dependence induced through Lévy's Copula. In this...

10.1080/10485252.2014.966103 article EN Journal of nonparametric statistics 2014-10-07

Let (Xn : n ≥ 1) be a sequence of random observations.Let σn(•) = P (Xn+1 ∈ • | X1, . ., Xn) the nth predictive distribution and σ0(•)=P (X1 •) marginal X1.To make predictions on (Xn), Bayesian forecaster needs only collection σ (σn 0).From Ionescu-Tulcea theorem, can assigned directly, without passing through usual prior/posterior scheme.One main advantage is that no prior probability has to selected.This point view adopted in this paper.The choice subject two requirements: (i) resulting...

10.5705/ss.202021.0238 article EN Statistica Sinica 2022-02-16

Abstract In this article, a new Pólya urn model is introduced and studied; in particular, strong law of large numbers two central limit theorems are proved. This generalizes studied Berti et al. (Citation2004), May (Citation2005), Crimaldi (Citation2007), it has natural applications clinical trials. Indeed, the includes both delayed missing (or null) responses. Moreover, connection with conditional identity distribution (Citation2004) given. Keywords: Almost sure coverageClinical...

10.1080/03610920802001888 article EN Communication in Statistics- Theory and Methods 2008-07-08

Normalized compound random measures are flexible nonparametric priors for related distributions. We consider building general regression models using normalized measure mixture models. Posterior inference is made a novel pseudo-marginal Metropolis-Hastings sampler The algorithm makes use of new approach to the unbiased estimation Laplace functionals (which includes completely as special case). illustrated on problems density regression.

10.1214/17-ba1072 article EN Bayesian Analysis 2017-10-26

The Yule–Simon distribution has been out of the radar Bayesian community, so far. In this note, we propose an explicit Gibbs sampling scheme when a Gamma prior is chosen for shape parameter. performance algorithm illustrated with simulation studies, including count data regression, and real application to text analysis. We compare our proposal frequentist counterparts showing better small sample size considered.

10.1080/00949655.2016.1255741 article EN Journal of Statistical Computation and Simulation 2016-11-13

The analysis of categorical response data through the multinomial model is very frequent in many statistical, econometric, and biometric applications. However, one main problems precise estimation parameters when number observations low. We propose a new Bayesian approach where prior distribution constructed transformation multivariate beta Olkin Liu (2003 , I. R. ( 2003 ). A bivariate . Stat. Probab. Lett. 62 : 407 – 412 .[Crossref], [Web Science ®] [Google Scholar]). Moreover, application...

10.1080/03610911003650375 article EN Communications in Statistics - Simulation and Computation 2010-03-31

The number of immigrants moving to and settling in Europe has increased over the past decade, making migration one most topical pressing issues European politics. It is without a doubt that immigration multiple impacts, terms economy, society culture, on Union. fundamental policy-makers correctly evaluate people's attitudes towards when designing integration policies. Of critical interest properly discriminate between subjects who are favourable from those against it. Public opinions...

10.1080/02664763.2019.1642310 article EN Journal of Applied Statistics 2019-07-18
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