In this paper, we propose augmented inverse probability weighted (AIPW) local estimating equations in dealing with missing data in nonparametric quantile regression context. The missing mechanism here is missing at ra...
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In this paper, we propose augmented inverse probability weighted (AIPW) local estimating equations in dealing with missing data in nonparametric quantile regression context. The missing mechanism here is missing at random. To avoid the problem of misspecification, we adopt nonparametric approach to estimate the propensity score and conditional expectations of estimating functions. The asymptotic properties of our proposed estimator are studied. Majorisation-minimisation algorithm is used to circumvent the nonsmoothness of check function at the origin. When it comes to the choice of bandwidth, the theoretical expression of local optimal bandwidth is derived based on asymptotic properties. Moreover, we apply smoothed bootstrap method to obtain the empirical mean square error and use cross-validation to determine the bandwidth in practice. Simulations are conducted to compare the performance of our proposed methods with other existing methods. Finally, we illustrate our methodology with an analysis of non-insulin-dependent diabetes mellitus data set.
This paper proposes a variable selection procedure for the nonparametric quantile regression based on the measurement error model (MEM). The "false" Gaussian measurement error is forced into the covariates t...
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This paper proposes a variable selection procedure for the nonparametric quantile regression based on the measurement error model (MEM). The "false" Gaussian measurement error is forced into the covariates to construct a nonparametric quantile regression loss function with the MEM framework. Under this MEM framework, the variable selection procedure is completed, and the asymptotic normality of the estimates and the consistency of variable selection are verified. Some Monte Carlo simulations and a real data application are conducted to evaluate the performance of the proposed procedure.
nonparametric quantile regression is a commonly used nonlinear quantile model. One general and popular approach is based on the use of kernels within a reproducing kernel Hilbert space (RKHS) framework, with the smoot...
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nonparametric quantile regression is a commonly used nonlinear quantile model. One general and popular approach is based on the use of kernels within a reproducing kernel Hilbert space (RKHS) framework, with the smoothing splines estimation as a special case. However, when the sample size n is large, the computational burden is heavy. Motivated by the recent advances in random projection for kernel nonparametric (mean) ridge regression (KRR), we consider an m-dimensional random projection approach for kernel quantileregression (KQR) with m << n. We establish a theoretical result showing that the sketched KQR still achieves the minimax convergence rate when m is at least as large as the effective statistical dimension of the problem. Some Monte Carlo studies are carried out for illustration purposes. (C) 2020 Elsevier Inc. All rights reserved.
Extreme events, such as earthquakes, tsunamis, and market crashes, can have substantial impact on social and ecological systems. quantileregression can be used for predicting these extreme events, making it an import...
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Extreme events, such as earthquakes, tsunamis, and market crashes, can have substantial impact on social and ecological systems. quantileregression can be used for predicting these extreme events, making it an important problem that has applications in many fields. Estimating high conditional quantiles is a difficult problem. Regular linear quantileregression uses an L-1 loss function [Koenker in quantileregression, Cambridge University Press, Cambridge, 2005], and the optimal solution of linear programming for estimating coefficients of regression. A problem with linear quantileregression is that the estimated curves for different quantiles can cross, a result that is logically inconsistent. To overcome the curves crossing problem, and to improve high quantile estimation in the nonlinear case, this paper proposes a nonparametric quantile regression method to estimate high conditional quantiles. A three-step computational algorithm is given, and the asymptotic properties of the proposed estimator are derived. Monte Carlo simulations show that the proposed method is more efficient than linear quantileregression method. Furthermore, this paper investigates COVID-19 and blood pressure real-world examples of extreme events by using the proposed method.
Nitrate (NO3-) pollution in groundwater is a major concern due to its negative health effects;therefore, accurately estimating and predicting the NO3- concentration in groundwater is necessary. The NO3- concentration ...
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Nitrate (NO3-) pollution in groundwater is a major concern due to its negative health effects;therefore, accurately estimating and predicting the NO3- concentration in groundwater is necessary. The NO3- concentration distribution can be used to find less polluted areas, and these identified areas can be candidates for drinking water resources. We considered a total of 14,297 NO3- concentration observations in South Korea. Altitude, slope, land use, hydrogeological unit, and surface soil texture data were also collected to assess the covariates that affect NO3- concentration levels. Sample quantiles display nonlinear patterns based on these covariates. Thus, we propose using an ensemble nonparametric quantile regression approach to determine the NO3- concentration distribution. The proposed approach is a data-driven method that ensembles nonlinear quantile models to capture the complex relationships between quantiles of the response variable and the covariates while controlling the computational complexity, which are advantages over non-ensemble quantileregression methods. The validation study demonstrates that the proposed method exhibits a smaller loss value compared to that of the non-ensemble models considered for comparison. We investigated lower quantile maps of NO3- concentration (5% and 10%), as we are interested in less polluted areas. The proposed model attempts to reach the sample quantile values while a non-ensemble nonlinear model with altitude and slope does not except land use is coniferous at low altitude. We created a proportional map with less polluted areas at the district level using the proposed approach. This provided us with the top five districts (Samcheok City, Geochang County, Yanggu County, Inje County, and Yeongwol County) with the highest proportions of less-polluted areas in South Korea. (C) 2021 Elsevier B.V. All rights reserved.
quantileregression with a total variation penalty was previously proposed due to its computational expediency as well as its local adaptiveness. However, the convergence rate of the method in this setting has been no...
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quantileregression with a total variation penalty was previously proposed due to its computational expediency as well as its local adaptiveness. However, the convergence rate of the method in this setting has been not rigorously established. In this short communication, we establish the convergence rate of O-p(n(-1/3)) for the penalized estimator which is the same as in penalized least squares regression. Different from penalized least squares regression, in order to deal with the quantile loss function, we heavily rely on the Rademacher complexity of the class of functions of bounded variation.
This article attempts to address the interesting and important research topic and to give an in-depth longitudinal study of Xining high school students using a so called "double-kernel" nonparametric quantil...
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This article attempts to address the interesting and important research topic and to give an in-depth longitudinal study of Xining high school students using a so called "double-kernel" nonparametric quantile regression approach. The conclusion is that the process-science-push's and process-math-push's points is 4, the result-science-push's point is 3, etc. All the findings are useful for parents understand students' learning status, especially for educators make educational plans.
In practical applications, one often does not know the 'true' structure of the underlying conditional quantile function, especially in the ultra-high dimensional setting. To deal with ultra-high dimensionality...
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In practical applications, one often does not know the 'true' structure of the underlying conditional quantile function, especially in the ultra-high dimensional setting. To deal with ultra-high dimensionality, quantile-adaptive marginal nonparametric screening methods have been recently developed. However, these approaches may miss important covariates that are marginally independent of the response, or may select unimportant covariates due to their high correlations with important covariates. To mitigate such shortcomings, we develop a conditional nonparametricquantile screening procedure (complemented by subsequent selection) for nonparametric additive quantileregression models. Under some mild conditions, we show that the proposed screening method can identify all relevant covariates in a small number of steps with probability approaching one. The subsequent narrowed best subset (via a modified Bayesian information criterion) also contains all the relevant covariates with overwhelming probability. The advantages of our proposed procedure are demonstrated through simulation studies and a real data example.
In this paper,we focus on the problem of nonparametric quantile regression with left-truncated and right-censored *** on Nadaraya-Watson(NW)Kernel smoother and the technique of local linear(LL)smoother,we construct th...
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In this paper,we focus on the problem of nonparametric quantile regression with left-truncated and right-censored *** on Nadaraya-Watson(NW)Kernel smoother and the technique of local linear(LL)smoother,we construct the NW and LL estimators of the conditional *** strong mixing assumptions,we establish asymptotic representation and asymptotic normality of the *** sample behavior of the estimators is investigated via simulation,and a real data example is used to illustrate the application of the proposed methods.
The considerable increase in municipal waste has become a primary global concern due to the contamination of the environment through the emission of greenhouse gases. Therefore, many OECD countries have adopted munici...
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The considerable increase in municipal waste has become a primary global concern due to the contamination of the environment through the emission of greenhouse gases. Therefore, many OECD countries have adopted municipal waste management practices. This study is a baseline attempt to explore the long-term effect of municipal waste management along with the energy transition, environmental innovation, and environmental policy stringency on GHG emissions in ten OECD countries from 1994 to 2020. This objective is realized by using non-parametric panel quantileregression. The estimated result reveals the asymmetric effect of selected explanatory variables on GHG emissions at various quantiles. The findings show that an increase in municipal waste can increase GHGs emissions at lower quantiles, while an insignificant effect is observed at higher quantiles. Similarly, energy transition, environmental innovation, and environmental policy stringency reveal asymmetric effects across the quantiles. The findings urge OECD countries to adopt more efficient municipal waste management practices and encourage renewable energy transition and environmental innovation. Envi-ronmental policy stringency can also be instrumental in enhancing environmental sustainability.
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