A Simple Class of Bayesian Nonparametric Autoregression Models

We introduce a model for a time series of continuous outcomes, that can be expressed as fully nonparametric regression or density regression on lagged terms. The model is based on a dependent Dirichlet process prior on a family of random probability measures indexed by the lagged covariates. The approach is also extended to sequences of binary responses. We discuss implementation and applications of the models to a sequence of waiting times between eruptions of the Old Faithful Geyser, and to a dataset consisting of sequences of recurrence indicators for tumors in the bladder of several patients.MIUR 2008MK3AFZFONDECYT 1100010NIH/NCI R01CA075981Mathematic

Bayesian functional emulation of CO2 emissions on future climate change scenarios

We propose a statistical emulator for a climate-economy deterministic integrated assessmentmodel ensemble, based on a functional regression framework. Inference on the unknown parameters is carried out through a mixed effects hierarchical model using a fully Bayesian framework with a prior distribution on the vector of all parameters. We also suggest an autoregressive parameterization of the covariance matrix of the error, with matching marginal prior. In this way, we allow for a functional framework for the discretized output of the simulators that allows their time continuous evaluation

Gender inequalities at work in Southern Europe

Despite a long-term trend towards reduction, the gender gap in employment keeps standing in Southern Europe. Numerous potential causes have been individuated, such as the household configuration, women’s human capital, or the institutions that regulate the labour market. Less is known about the role of the locality. This paper explores what covariates influence women’s access to labour markets, and whether it is unevenly distributed across different countries and regions in Southern Europe. The analysis is based on the dataset round 9 (2018) from the European Social Survey. We focus on the following countries available in the dataset: Cyprus, Italy, Spain and Portugal. Italy and Spain are further differentiated into vulnerable and affluent regions according to the regional GDP in 2018. We apply a regression model for the binary response that is the indicator of having been doing paid work for the last 7 days of each individual in the sample. We adopt the Bayesian approach, to derive conclusions via a whole probability distribution, i.e., the posterior of all parameters, given data. The statistical goal is the selection of the most important covariates for access to the labour market, focusing on gender differences. Our analysis finds out that individual characteristics are mediated by household composition. Even though higher education increases women’s employment, the presence of children and having an employed partner reduce such involvement. Moreover, a larger gender gap is detected in vulnerable regions rather than affluent ones, especially in Italy

A class of measure-valued Markov chains and Bayesian nonparametrics

Measure-valued Markov chains have raised interest in Bayesian nonparametrics since the seminal paper by (Math. Proc. Cambridge Philos. Soc. 105 (1989) 579--585) where a Markov chain having the law of the Dirichlet process as unique invariant measure has been introduced. In the present paper, we propose and investigate a new class of measure-valued Markov chains defined via exchangeable sequences of random variables. Asymptotic properties for this new class are derived and applications related to Bayesian nonparametric mixture modeling, and to a generalization of the Markov chain proposed by (Math. Proc. Cambridge Philos. Soc. 105 (1989) 579--585), are discussed. These results and their applications highlight once again the interplay between Bayesian nonparametrics and the theory of measure-valued Markov chains.Comment: Published in at http://dx.doi.org/10.3150/11-BEJ356 the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

The semi-hierarchical Dirichlet Process and its application to clustering homogeneous distributions

Assessing homogeneity of distributions is an old problem that has received considerable attention, especially in the nonparametric Bayesian literature. To this effect, we propose the semi-hierarchical Dirichlet process, a novel hierarchical prior that extends the hierarchical Dirichlet process of Teh et al. (2006) and that avoids the degeneracy issues of nested processes recently described by Camerlenghi et al. (2019a). We go beyond the simple yes/no answer to the homogeneity question and embed the proposed prior in a random partition model; this procedure allows us to give a more comprehensive response to the above question and in fact find groups of populations that are internally homogeneous when I greater or equal than 2 such populations are considered. We study theoretical properties of the semi-hierarchical Dirichlet process and of the Bayes factor for the homogeneity test when I = 2. Extensive simulation studies and applications to educational data are also discussed

Spatially dependent mixture models via the Logistic Multivariate CAR prior

We consider the problem of spatially dependent areal data, where for each area independent observations are available, and propose to model the density of each area through a finite mixture of Gaussian distributions. The spatial dependence is introduced via a novel joint distribution for a collection of vectors in the simplex, that we term logisticMCAR. We show that salient features of the logisticMCAR distribution can be described analytically, and that a suitable augmentation scheme based on the P\'olya-Gamma identity allows to derive an efficient Markov Chain Monte Carlo algorithm. When compared to competitors, our model has proved to better estimate densities in different (disconnected) areal locations when they have different characteristics. We discuss an application on a real dataset of Airbnb listings in the city of Amsterdam, also showing how to easily incorporate for additional covariate information in the model