Search results for " Probability"
showing 10 items of 2176 documents
Locally weighted minimum contrast estimation for spatio-temporal log-Gaussian Cox processes
2023
A local version of spatio-temporal log-Gaussian Cox processes is proposed by using Local Indicators of Spatio-Temporal Association (LISTA) functions plugged into the minimum contrast procedure, to obtain space as well as time-varying parameters. The new procedure resorts to the joint minimum contrast fitting method to estimate the set of second-order parameters. This approach has the advantage of being suitable in both separable and non-separable parametric specifications of the correlation function of the underlying Gaussian Random Field. Simulation studies to assess the performance of the proposed fitting procedure are presented, and an application to seismic spatio-temporal point pattern…
Bayesian joint models for longitudinal and survival data
2020
This paper takes a quick look at Bayesian joint models (BJM) for longitudinal and survival data. A general formulation for BJM is examined in terms of the sampling distribution of the longitudinal and survival processes, the conditional distribution of the random effects and the prior distribution. Next a basic BJM defined in terms of a mixed linear model and a Cox survival regression models is discussed and some extensions and other Bayesian topics are briefly outlined.
The Integrated Nested Laplace Approximation for fitting Dirichlet regression models
2022
This paper introduces a Laplace approximation to Bayesian inference in Dirichlet regression models, which can be used to analyze a set of variables on a simplex exhibiting skewness and heteroscedasticity, without having to transform the data.These data, which mainly consist of proportions or percentages of disjoint categories, are widely known as compositional data and are common in areas such as ecology, geology, and psychology. We provide both the theoretical foundations and a description of how Laplace approximation can be implemented in the case of Dirichlet regression.The paper also introduces the package dirinla in the R-language that extends the RINLA package, which can not deal dire…
Covariate-informed latent interaction models: Addressing geographic & taxonomic bias in predicting bird-plant interactions
2023
Reductions in natural habitats urge that we better understand species' interconnection and how biological communities respond to environmental changes. However, ecological studies of species' interactions are limited by their geographic and taxonomic focus which can distort our understanding of interaction dynamics. We focus on bird-plant interactions that refer to situations of potential fruit consumption and seed dispersal. We develop an approach for predicting species' interactions that accounts for errors in the recorded interaction networks, addresses the geographic and taxonomic biases of existing studies, is based on latent factors to increase flexibility and borrow information acros…
Entry under uncertainty: Limit and most-favored-customer pricing
2015
Abstract In the absence of uncertainty, an incumbent that attempts to prevent entry of rival firms can have no incentive to offer a most-favored-customer (MFC) clause because it could lead to higher post-entry prices. Our analysis suggests that this is not necessarily the case under uncertainty. In the presence of uncertainty, the incumbent can set a limit price that affects the entry decision. Limit pricing involves a pre-entry price different from the static monopoly price, which leads to a signaling cost. We show that part of this cost can be distributed over several periods by means of consumer refunds from the MFC clause. If the discount factor is not very high, the incumbent adopts th…
Partially revocable commitments in a negotiation with a deadline
2004
Abstract [Fershtman, C., Seidmann, D., 1993. Deadline effects and inefficient delay in bargaining with endogenous commitment. Journal of Economic Theory 60, 306–321] showed that the presence of an irrevocable endogenous commitment with a fixed deadline results in the so called deadline effect. In this paper we analyse the effects of partially revocable endogenous commitments of a seller in an infinite horizon negotiation in which a deadline can arise with positive probability. We obtain that when the commitment possesses a sufficiently large revocable part not only the inefficient delays disappear and an immediate agreement is reached but also the commitment has a value. On the other hand, …
A Bayesian direction-of-arrival model for an undetermined number of sources using a two-microphone array.
2014
Sound source localization using a two-microphone array is an active area of research, with considerable potential for use with video conferencing, mobile devices, and robotics. Based on the observed time-differences of arrival between sound signals, a probability distribution of the location of the sources is considered to estimate the actual source positions. However, these algorithms assume a given number of sound sources. This paper describes an updated research account on the solution presented in Escolano et al. [J. Acoust. Am. Soc. 132(3), 1257-1260 (2012)], where nested sampling is used to explore a probability distribution of the source position using a Laplacian mixture model, whic…
The migrant crisis in the Mediterranean Sea: Empirical evidence on policy interventions
2021
Abstract This paper presents a novel set of empirical evidence to explore several hypotheses regarding the migrant crisis in the Mediterranean Sea. The political instability in transit countries, such as Libya, that made pre-existent repatriation policies ineffective, called for several search-and-rescue operations in the Mediterranean, which in turn have been wrongly accused of fostering illegal immigration and increasing deaths at sea. The empirical results show that the main determinants of the departures are several root causes at the departing African countries, underlining the importance of fighting human smuggling networks. The paper suggests a change in migration studies’ perspectiv…
Graph Topology Learning and Signal Recovery Via Bayesian Inference
2019
The estimation of a meaningful affinity graph has become a crucial task for representation of data, since the underlying structure is not readily available in many applications. In this paper, a topology inference framework, called Bayesian Topology Learning, is proposed to estimate the underlying graph topology from a given set of noisy measurements of signals. It is assumed that the graph signals are generated from Gaussian Markov Random Field processes. First, using a factor analysis model, the noisy measured data is represented in a latent space and its posterior probability density function is found. Thereafter, by utilizing the minimum mean square error estimator and the Expectation M…
Annual flow duration curves assessment in ephemeral small basins
2014
Flow duration curve (FDC) represents a comprehensive signature of temporal runoff variability often used to synthesize catchment rainfall-runoff responses. A new model, the ModABa (MODel for Annual flow duration curves assessment in ephemeral small BAsins), is here introduced. It can be thought as a wide mosaic whose tesserae are frameworks, models or conceptual schemes separately developed in different studies and harmoniously interconnected with the final aim of reproducing the annual FDC in intermittent small catchments. Two separated seasons within the hydrological year are distinguished: a dry season, characterized by absence of streamflow, and a non-zero season. Streamflow is disaggre…