37 documents found, page 1 of 4
Bayesian Modelling of Time Series of Counts with Missing Data
Silva, Isabel; Silva, Maria Eduarda; Pereira, IThe presence of missing data poses a common challenge for time series analysis in general since the most usual requirement is that the data is equally spaced in time and therefore imputation methods are required. For time series of counts, the usual imputation methods which usually produce real valued observations, are not adequate. This work employs Bayesian principles for handling missing data within time ser...
Implications of seasonal and daily variation on methane and ammonia emissions f...
Rodrigues, Ana R.F.; Silva, Maria Eduarda; Silva, Vanessa F.; Maia, Margarida R.G.; Cabrita, Ana R.J.; Trindade, Henrique; Fonseca, António J.M.Seasonal and daily variations of gaseous emissions from naturally ventilated dairy cattle barns are important figures for the establishment of effective and specific mitigation plans. The present study aimed to measure methane (CH4) and ammonia (NH3) emissions in three naturally ventilated dairy cattle barns covering the four seasons for two consecutive years. In each barn, air samples from five indoor location...
Time series of counts under censoring: a Bayesian approach
Silva, Isabel; Silva, Maria Eduarda; Pereira, Isabel; McCabe, BrendanCensored data are frequently found in diverse fields including environmental monitoring, medicine, economics and social sciences. Censoring occurs when observations are available only for a restricted range, e.g., due to a detection limit. Ignoring censoring produces biased estimates and unreliable statistical inference. The aim of this work is to contribute to the modelling of time series of counts under censo...
Censored multivariate linear regression model
Pereira, Isabel; Sousa, Rodney; Silva, Maria EduardaOften, real life problems require modelling several response variables together. This work analyses multivariate linear regression model when the data are censored. Censoring distorts the correlation structure of the underlying variables and increases the bias of the usual estimators. Thus, we propose three methods to deal with multivariate data under left censoring, namely, Expectation Maximization (EM), Data ...
Bayesian modeling time series of counts under censoring
Pereira, Isabel; Silva, Isabel; Silva, Maria Eduarda; McCabe, BrendanCensored time series arisedwhen explicit limits are placed on observed data and occur in several fields including environmental monitoring, economics, medical and social sciences. The censoring may be due to measuring device limitation, such as detection limits in air pollution or mineral concentration in water. Censoring may also occur when constraints or regulations are imposed, such as in international trade...
Modelling informative time points: an evolutionary process approach
Monteiro, Andreia Alves Forte Oliveira; Menezes, Raquel; Silva, Maria EduardaReal time series sometimes exhibit various types of "irregularities": missing observations, observations collected not regularly over time for practical reasons, observation times driven by the series itself, or outlying observations. However, the vast majority of methods of time series analysis are designed for regular time series only. A particular case of irregularly spaced time series is that in which the s...
O entendimento do Tribunal de Justiça de Santa Catarina acerca da aplicabilidad...
Silva, Maria EduardaEste trabalho monográfico tem por objetivo verificar a possibilidade de conceder-se indenização por dano moral diante da conduta do (a) genitor (a) que abandona afetivamente seu filho. Para tanto, fora realizado o levantamento bibliográfico de doutrinadores e juristas sobre o tema em voga, perpassando sobre as principais matérias que atingem o problema proposto, sendo estes, a evolução histórica da família e do...
Análise de regressão linear com autocorrelação nos erros para dados censurados
Sousa, Rodney; Pereira, Isabel; Silva, Maria EduardaEste trabalho aborda, numa perspetiva bayesiana, a análise de modelos de regressão linear com erros autocorrelacionados para dados censurados, recorrendo a métodos Computacionais Bayesianos Aproximados (ABC) e ao amostrador de Gibbs com a Ampliação de Dados (GDA). Considera-se que o termo dos erros segue um processo autorregressivo, AR, e investiga-se o desempenho dos métodos através de dois estudos de simulaçã...
Dynamic structural models with covariates for short-term forecasting of time se...
Puindi, António Casimiro; Silva, Maria EduardaThis work presents a framework of dynamic structural models with covariates for short-term forecasting of time series with complex seasonal patterns. The framework is based on the multiple sources of randomness formulation. A noise model is formulated to allow the incorporation of randomness into the seasonal component and to propagate this same randomness in the coefficients of the variant trigonometric terms ...
Time series analysis via network science: concepts and algorithms
Silva, Vanessa Freitas; Silva, Maria Eduarda; Ribeiro, Pedro; Silva, FernandoThere is nowadays a constant flux of data being generated and collected in all types of real world systems. These data sets are often indexed by time, space or both requiring appropriate approaches to analyze the data. In univariate settings, time series analysis is a mature and solid field. However, in multivariate contexts, time series analysis still presents many limitations. In order to address these issues...