593 research outputs found
A dynamic structural equation approach to estimate the short-term effects of air pollution on human health.
No full textDetailed knowledge on the effects of air pollutants on human health is a prerequisite for the development of effective policies to reduce the adverse impact of ambient air pollution. However, measuring the effect of exposure on health outcomes is an extremely difficult task as the health impact of air pollution is known to vary over space and over different exposure periods. In general, standard approaches aggregate the information over space or time to simplify the study but this strategy fails to recognize important regional differences and runs into the well-known risk of confounding the effects. However, modelling directly with the original, disaggregated data requires a highly dimensional model with the curse of dimensionality making inferences unstable; in these cases, the models tend to retain many irrelevant components and most relevant effects tend to be attenuated. The situation clearly calls for an intermediate solution that does not blindly aggregate data while preserving important regional features. We propose a dimension-reduction approach based on latent factors driven by the data. These factors naturally absorb the relevant features provided by the data and establish the link between pollutants and health outcomes, instead of forcing a necessarily high-dimensional link at the observational level. The dynamic structural equation approach is particularly suited for this task. The latent factor approach also provides a simple solution to the spatial misalignment caused by using variables with different spatial resolutions and the state-space representation of the model favours the application of impulse response analysis. Our approach is discussed through the analysis of the short-term effects of air pollution on hospitalization data from Lombardia and Piemonte regions (Italy)
Space–time modelling of coupled spatiotemporal environmental variables
No full textThe paper is concerned with a dynamic factor model for spatiotemporal coupled
environmental variables. The model is proposed in a state space formulation which, through
Kalman recursions, allows a unified approach to prediction and estimation. Full probabilistic inference
for the model parameters is facilitated by adapting standard Markov chain Monte Carlo
algorithms for dynamic linear models to our model formulation.The predictive ability of the model
is discussed for two different data sets with variables measured at two different scales. Some
possibilities for further research are also outlined
A bayesian approach to hybrid splines non-parametric regression
No full textA Bayesian approach is considered to estimate the number of basis functions and the smoothing parameter of the hybrid splines non-parametric regression procedure. The method used to obtain the estimate of the regression curve and its Bayesian confidence intervals is based on the reversible jump MCMC (Green 1995). Illustrations with simulated data are provided and show good performance of the proposed approach over the existing methods.A Bayesian approach is considered to estimate the number of basis functions and the smoothing parameter of the hybrid splines non-parametric regression procedure. The method used to obtain the estimate of the regression curve and its Bayesian confidence i724285297FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPERJ - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIRO95=4996-3; 99=00261-0259=98450560=98; 300644=94-9SEM INFORMAÇÃOWe would like to thank the Associate Editor and the referees for the comments and suggestions that made this work better and clearer. Also, the first author would like to thank Prof. Michael Newton and Prof. Mary Lindstrom for all suggestion made during
Dynamic analysis of survival models and related processes.
No full textThis thesis presents new methods of analysis of survival data based on a Dynamic Bayesian approach. The models allow the parameters to change with time. The analysis is tractable and emphasises predictive aspects of the models. The survival problems covered include linear and non-linear regression, analysis of random samples, time-dependent covariates, life tables and competing risks. The analysis is also extended to a number of point processes. Numerical applications are provided and the microcomputer software to perform them is described
Modelos dinâmicos e simulação estocástica
No full textThis paper presents new methodology for making Bayesian inference about dy~ o!s for exponential famiIy observations. The approach is simulation-based _~t> use of ~vlarkov chain Monte Carlo techniques. A yletropolis-Hastings i:U~UnLlllll 1::; combined with the Gibbs sampler in repeated use of an adjusted version of normal dynamic linear models. Different alternative schemes are derived and compared. The approach is fully Bayesian in obtaining posterior samples for state parameters and unknown hyperparameters. Illustrations to real data sets with sparse counts and missing values are presented. Extensions to accommodate for general distributions for observations and disturbances. intervention. non-linear models and rnultivariate time series are outlined
CITRA PEREMPUAN SUKU DANI DALAM NOVEL ETNOGRAFI SALI, KISAH SEORANG WANITA SUKU DANI KARYA DEWI LINGGASARI: ANALISIS KRITIK SASTRA FEMINIS RUTHVEN
No full textThe research conducted on a novel tittled Sali, The Story of a Dani Woman
(SKSWSD) by Linggasari aims to contribute ideas on the study of women,
especially images of Dani women by using feminist literary criticism from
Ruthven. Dani women live in a patriarchal system that treats women in a
disadvantageous position. In this research, the concept images of women is used
to reveal the nature of stereotype representation of women oppression. In
ethnographic novel SKSWSD, the author tried to criticize the patriarchal system
that is represented from Dani female figures with their life background, there by it
establishes the image of Dani women.
The results from the character identification shows that there contrafeminist
and profeminist characters in the middle of patriarchal culture. The analysis of
language aspects are used for the reflection of Dani women�s image. According to
the analysis of aspects of language usage, there are three conceptions. First, the
language showed gender differences. Second, the language refers to the symbols
of feminine and masculine. Third, as a form of criticism from women toward men
in the middle of patriarchal culture. The ideology of women's imaging proves that
women rule over theirself, always trying to be free from male dominance, and
they have right to get education. Analysis of the image of women shows Dani
women have image in the domestic sector and the image in the public sector.
Based on the research, it can be concluded that novel ethnography SKSWSD
raises the problems of women who live in the middle of the patriarchal system.
The female characters in the novel have to make a protest action for the gender
inequality they get, not merely an idea or discourse of feminism
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