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Chong Gu

Publications and source records attributed to Chong Gu.

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Retrospective Statistical Inference

In this article, we explore a new paradigm for statistical inference. The approach centers around the point estimate based on observed data, simulating replicates using the estimate as the truth to produce clones of the estimate, with inference deriving from the clone distribution. It avoids prospective finite-dimensional model assumptions, but it makes no probabilistic claims concerning the truth; it suggests an alternative system of uncertainty quantification that is operable in nonparametric function estimation. The procedures are demonstrated using examples of smoothing spline ANOVA models in nonparametric regression. The paradigm also applies in parametric regression, where the proposed inference closely resembles traditional inference operation-wise. Conceptual discussions are scattered throughout.

stat.ME

A Green's function approach to linearized Monge-Amp\`ere equations in divergence form and application to singular Abreu type equations

In this paper, we establish local and global regularity estimates for linearized Monge-Amp\`ere equations in divergence form via critical Lorentz space estimates for the Green's function of the linearized Monge-Amp\`ere operator and its gradient. These estimates hold under suitable conditions on the data and the convex Monge-Amp\`ere potential is assumed to have Hessian determinant bounded between two positive constants. As an application, we obtain the solvability in all dimensions of the second boundary value problem for a class of singular fourth-order Abreu type equations that arise from the approximation analysis of variational problems subject to convexity constraints.

math.AP

Composition Estimation via Shrinkage

In this note, we explore a simple approach to composition estimation, using penalized likelihood density estimation on a nominal discrete domain. Practical issues such as smoothing parameter selection and the use of prior information are investigated in simulations, and a theoretical analysis is attempted. The method has been implemented in a pair of R functions for use by practitioners.

stat.ME

Optimal smoothing in nonparametric mixed-effect models

Mixed-effect models are widely used for the analysis of correlated data such as longitudinal data and repeated measures. In this article, we study an approach to the nonparametric estimation of mixed-effect models. We consider models with parametric random effects and flexible fixed effects, and employ the penalized least squares method to estimate the models. The issue to be addressed is the selection of smoothing parameters through the generalized cross-validation method, which is shown to yield optimal smoothing for both real and latent random effects. Simulation studies are conducted to investigate the empirical performance of generalized cross-validation in the context. Real-data examples are presented to demonstrate the applications of the methodology.

math.ST