Comparison of Weighted Estimation Methods for the Varying Coefficient Quantile Regression Model in the Case of Longitudinal Data

Authors

  • Ali Mohammed Farhan Department of Statistics , College of Administration and Economics , University of Baghdad , Iraq Author
  • Mohammed Sadiq Abdul Razzaq Department of Statistics , College of Administration and Economics , University of Baghdad , Iraq Author

DOI:

https://doi.org/10.62933/q04zh103

Keywords:

Longitudinal data analysis, , Quantile regression,, Weighted local polynomial,, Weighted Spline

Abstract

In this study, two weighted methods are proposed for estimating the varying coefficient quantile regression model in the case of longitudinal data. The first method is the Weighted Spline Method, and the second is the Weighted Local Polynomial Method. Both methods account for within-subject correlations, which are addressed by incorporating weights derived from the empirical likelihood of each method. Five levels of quantiles were examined, and a simulation study was conducted to compare the two methods under different conditions. The methods were applied to the success rates data of the third intermediate grade in Al-Diwaniyah Governorate, assessing the impact of four explanatory variables on the success rates of 337 middle and secondary schools over five years. Results indicated that the efficiency of the methods varied across quantile levels: the Weighted Spline Method was more efficient at high and low quantile levels, whereas the Weighted Local Polynomial Method proved more efficient at intermediate levels.

References

Badr, Duraid H. (2016). The diagnosis estimation of the nonparametric regression function of the panel data in Case some of its hypotheses are not verified. The Ph. D to the College of Administration and Economics, University of Baghdad.

[2] Cai, Z., & Xu, X. 2008. Nonparametric quantile estimations for dynamic smooth coefficient models. Journal of the American Statistical Association, 103(484), 1595-1608.‏

[3] Fu, L., & Wang, Y. G. (2012). Quantile regression for longitudinal data with a working correlation model. Computational Statistics & Data Analysis, 56(8), 2526-2538.

[4] Hoover, D. R., Rice, J. A., Wu, C. O., & Yang, L. P. (1998). Nonparametric smoothing estimates of time-varying coefficient models with longitudinal data. Biometrika, 85(4), 809-822.

[5] Karlsson, A. (2007). Nonlinear quantile regression estimation of longitudinal data. Communications in Statistics-Simulation and Computation, 37(1), 114-131.‏

[6] Kim, M. O. (2007). Quantile regression with varying coefficients.‏ Ann. Statist. 35(1): 92-108.

[7] Kim, S., & Cho, H. R. (2018). Efficient estimation in the partially linear quantile regression model for longitudinal data.‏ Electron. J. Statist. 12(1): 824-850

[8] Kim, S., & Cho, H. R. (2018). Efficient estimation in the partially linear quantile regression model for longitudinal data.‏ Electron. J. Statist. 12(1): 824-850.

[9] Koenker, R., & Bassett Jr, G. (1978) . Regression quantiles. Econometrica: journal of the Econometric Society, 33-50.‏

[10] Lin, F., Tang, Y., & Zhu, Z. (2020). Weighted quantile regression in varying-coefficient model with longitudinal data. Computational Statistics & Data Analysis, 145, 106915.

[11] Liu, S. (2017). Efficient estimation of longitudinal data additive varying coefficient regression models. Acta Mathematicae Applicatae Sinica, English Series, 33, 529-550.‏

[12] Lv, J., Guo, C., & Wu, J. (2019). Smoothed empirical likelihood inference via the modified Cholesky decomposition for quantile varying coefficient models with longitudinal data. Test, 28, 999-1032.‏

[13] Mu, Y., & Wei, Y. (2009). A dynamic quantile regression transformation model for longitudinal data. Statistica Sinica, 1137-1153.

[14] Qu, A., & Li, R. (2006). Quadratic inference functions for varying-coefficient models with longitudinal data. Biometrics, 62(2), 379-391.‏

[15] Qu, A., Lindsay, B. G., & Li, B. (2000). Improving generalised estimating equations using quadratic inference functions. Biometrika, 87(4), 823-836.‏

[16] Rashed, Husam A. and Rasheed, Dhafir H. (2014). Comparison between the Local Polynomial Kernel and Penalized Spline to Estimating Varying Coefficient Model. Journal of Economics And Administrative Sciences, 20(78).‏

[17] Saifalddin, Ali. And Rasheed, Dhafir H. (2013). Comparison Robust M Estimate with Cubic Smoothing Splines for Time-Varying Coefficient Model for Balance Longitudinal Data. journal of Economics And Administrative Sciences, 19(73).

[18] Schwarz, G. (1978). Estimating the dimension of a model. The annals of statistics, 461-464.‏

[19] Song, P. X. K., Jiang, Z., Park, E., & Qu, A. (2009). Quadratic inference functions in marginal models for longitudinal data. Statistics in medicine, 28(29), 3683-3696.‏

[20] Tang, C. Y., & Leng, C.( 2011) . Empirical likelihood and quantile regression in longitudinal data analysis. Biometrika, 98(4), 1001-1006.‏

[21] Tang, Y., Wang, H. J., & Zhu, Z. (2013). Variable selection in quantile varying coefficient models with longitudinal data. Computational Statistics & Data Analysis, 57(1), 435-449.‏

[22] Wang, H. J., & Zhu, Z. (2011). Empirical likelihood for quantile regression models with longitudinal data. Journal of statistical planning and inference, 141(4), 1603-1615.‏

[23] Wu, C. O., & Chiang, C. T. (2000). Kernel smoothing on varying coefficient models with longitudinal dependent variable. Statistica Sinica, 433-456.

[24] Yu, K., & Jones, M. (1998). Local linear quantile regression. Journal of the American statistical Association, 93(441), 228-237.

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Published

2025-05-11

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Section

Original Articles

How to Cite

Comparison of Weighted Estimation Methods for the Varying Coefficient Quantile Regression Model in the Case of Longitudinal Data. (2025). Iraqi Statisticians Journal, 2(special issue for ICSA2025), 318-330. https://doi.org/10.62933/q04zh103