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Post-shrinkage strategies for nonlinear semiparametric regression models in low and high-dimensional settings

  • S. Ejaz Ahmed , Dursun Aydın and Ersin Yılmaz EMAIL logo
Published/Copyright: November 20, 2025

Abstract

This paper considers semiparametric estimation strategies for the nonlinear semiparametric regression model (NSRM) under the sparsity assumption by modifying the Gauss–Newton method for both low- and high-dimensional data scenarios. In the low-dimensional case, coefficients are partitioned into two parts that represent nonzero (strong signals) and sparse coefficients. In the high-dimensional case, a weighted-ridge approach is employed, and coefficients are partitioned into three parts, adding weak signals as well. Shrinkage estimators are then obtained in both cases. More importantly, in this paper, we assume that a nonlinear structure is present in the parametric component of the model, which makes the direct application of penalized least squares to the NSRM impossible. To solve this problem, we employ the iterative Gauss–Newton method to obtain the final NSRM estimators. We provide both theoretical and practical details for the suggested estimators. Asymptotic results are derived for both low- and high-dimensional cases. We conduct an extensive simulation study to evaluate the performance of the estimators in a practical setting. Moreover, we substantiate our findings with data examples from two distinct breast cancer datasets: the Breast Cancer in the United States (BCUS) and Wisconsin datasets. By demonstrating the effectiveness of our introduced estimators in these particular biostatistical contexts, our numerical study provides support for the theoretical efficacy of shrinkage estimators, suggesting their potential relevance to breast cancer research and biostatistical methodologies.


Corresponding author: Ersin Yılmaz, Department of Statistics, Faculty of Science, Mugla Sitki Kocman University, Mugla, 48000, Türkiye, E-mail: 

Award Identifier / Grant number: 1059B142100231

Acknowledgments

The research of Professor S. Ejaz Ahmed was supported by the Natural Sciences and the Engineering Research Council (NSERC) of Canada.

  1. Research ethics: Not applicable.

  2. Informed consent: Not applicable.

  3. Author contributions: Conceptualization: S.E.A. & D.A., Supervision: S.E.A., Design: E.Y. & D.A., Funding: E.Y., Analysis: D.A. & E.Y., Application and Coding: E.Y. & D.A., Review: S.E.A.

  4. Use of Large Language Models, AI and Machine Learning Tools: None declared.

  5. Conflict of interest: The authors do not have conflict of interest.

  6. Research funding: This paper is funded by the program of Scientific and Technological Research Council of Turkey BIDEB-2214-A with the Project No: 1059B142100231.

  7. Data availability: Breast Cancer Wisconsin dataset: https://www.kaggle.com/datasets/uciml/breast-cancer-wisconsin-data Breast Cancer in the United States (BCUS): https://data.world/deviramanan2016/nki-breast-cancer-data.

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Supplementary Material

This article contains supplementary material (https://doi.org/10.1515/ijb-2024-0011).


Received: 2024-02-06
Accepted: 2025-10-23
Published Online: 2025-11-20

© 2025 Walter de Gruyter GmbH, Berlin/Boston

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