5,413 research outputs found
Spatial analysis of risk factors for childhood morbidity in Nigeria
Recent Demographic and Health Surveys (DHS) from Sub-Saharan Africa (SSA) indicate a decline in
childhood vaccination coverage but a high prevalence of childhood diarrhea, cough, and fever. We used Nigerian DHS
data to investigate the impact of geographical factors and other important risk factors on diarrhea, cough, and fever using
geoadditive Bayesian semiparametric models. A higher prevalence of childhood diarrhea, cough, and fever is observed
in the northern and eastern states, while lower disease prevalence is observed in the western and southern states. In
addition, children from mothers with higher levels of education and those from poor households had a significantly lower
association with diarrhea; children delivered in hospitals, living in urban areas, or from mothers having received prenatal
visits had a significantly lower association with fever. Our maps are a novel and relevant tool to help local governments
to improve health-care interventions and achieve Millennium Development Goals (MDG4)
On the Bernstein-von Mises phenomenon for nonparametric Bayes procedures
We continue the investigation of Bernstein-von Mises theorems for
nonparametric Bayes procedures from [Ann. Statist. 41 (2013) 1999-2028]. We
introduce multiscale spaces on which nonparametric priors and posteriors are
naturally defined, and prove Bernstein-von Mises theorems for a variety of
priors in the setting of Gaussian nonparametric regression and in the i.i.d.
sampling model. From these results we deduce several applications where
posterior-based inference coincides with efficient frequentist procedures,
including Donsker- and Kolmogorov-Smirnov theorems for the random posterior
cumulative distribution functions. We also show that multiscale posterior
credible bands for the regression or density function are optimal frequentist
confidence bands.Comment: Published in at http://dx.doi.org/10.1214/14-AOS1246 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Prediction of time series by statistical learning: general losses and fast rates
We establish rates of convergences in time series forecasting using the
statistical learning approach based on oracle inequalities. A series of papers
extends the oracle inequalities obtained for iid observations to time series
under weak dependence conditions. Given a family of predictors and
observations, oracle inequalities state that a predictor forecasts the series
as well as the best predictor in the family up to a remainder term .
Using the PAC-Bayesian approach, we establish under weak dependence conditions
oracle inequalities with optimal rates of convergence. We extend previous
results for the absolute loss function to any Lipschitz loss function with
rates where measures the
complexity of the model. We apply the method for quantile loss functions to
forecast the french GDP. Under additional conditions on the loss functions
(satisfied by the quadratic loss function) and on the time series, we refine
the rates of convergence to . We achieve for the
first time these fast rates for uniformly mixing processes. These rates are
known to be optimal in the iid case and for individual sequences. In
particular, we generalize the results of Dalalyan and Tsybakov on sparse
regression estimation to the case of autoregression
Fully Bayesian Penalized Regression with a Generalized Bridge Prior
We consider penalized regression models under a unified framework. The
particular method is determined by the form of the penalty term, which is
typically chosen by cross validation. We introduce a fully Bayesian approach
that incorporates both sparse and dense settings and show how to use a type of
model averaging approach to eliminate the nuisance penalty parameters and
perform inference through the marginal posterior distribution of the regression
coefficients. We establish tail robustness of the resulting estimator as well
as conditional and marginal posterior consistency for the Bayesian model. We
develop a component-wise Markov chain Monte Carlo algorithm for sampling.
Numerical results show that the method tends to select the optimal penalty and
performs well in both variable selection and prediction and is comparable to,
and often better than alternative methods. Both simulated and real data
examples are provided
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