Sains
Malaysiana 55(8)(2026): 1393-1404
http://doi.org/10.17576/jsm-2026-5508-14
Bayesian
Regularized Quantile Beta Regression for Robust Estimation in Skewed Bounded
Data
(Regresi
Beta Kuantil Teratur Bayesian untuk Penganggaran Teguh dalam Data Pencong Terbatas)
FEDAA
NOEEL ABDULAHAD1,2, MAJID KHAN MAJAHAR ALI2,* & ALAA
ADNAN3
1University
of Al Hamdaniya, College of Education, Department of Mathematics, Mosul-Iraq
2School
of Mathematical Sciences, Universiti Sains Malaysia, 11800 USM, Penang,
Malaysia
3University of Glasgow,
James Watt School of Engineering, Glasgow, United Kingdom
Diserahkan: 26 November 2025/Diterima: 17 Ogos 2026
Abstract
Skewed
distributions often contain shape parameters that determine the direction and
magnitude of asymmetry. In other cases, skewness arises naturally from the form
of the distribution. Ignoring skewness when modeling with symmetric
distributions may yield biased or misleading inferences. Bayesian regularized
quantile regression has proven effective for skewed responses, yet existing
approaches rely on the asymmetric Laplace distribution (ALD), whose unbounded
support makes it unsuitable for bounded data. To address this limitation, we
propose a Bayesian Regularized Quantile Beta Regression (BRQBR) model for
analyzing bounded data supported on (0,1) with inherent skewness. The proposed
model estimates conditional quantiles of a Beta-distributed response using a
hierarchical Bayesian regularization framework with global–local shrinkage
priors. A Gibbs sampler is developed for posterior computation, and the model's
performance is evaluated under different skewness levels and contamination
scenarios (5% and 10% outliers) using Beta and logit-normal distributions. Application
to a real-world seaweed drying dataset demonstrates consistent improvements in
predictive accuracy. Across simulation and empirical analysis, BRQBR
outperforms or matches maximum likelihood estimation (MLE) while exhibiting
strong robustness to outliers. The proposed framework offers a flexible and
accurate solution for modeling skewed bounded responses.
Keywords: Bayesian
quantile regression; Beta distribution; robust regression; skewness
Abstrak
Taburan
pencong selalunya mengandungi parameter bentuk yang menentukan arah dan
magnitud asimetri. Dalam kes lain, kepencongan timbul secara semula jadi
daripada bentuk taburan. Mengabaikan kepencongan semasa pemodelan dengan
taburan simetri boleh menghasilkan inferens yang berat sebelah atau
mengelirukan. Regresi kuantil terlaras Bayesian telah terbukti berkesan untuk
tindak balas pencong, namun pendekatan sedia ada bergantung pada taburan
Laplace asimetri (ALD), yang sokongan tidak terbatasnya menjadikan ia tidak
sesuai untuk data terbatas. Untuk menangani batasan ini, kami mencadangkan
model Regresi Beta Kuantil Teratur Bayesian (BRQBR) untuk menganalisis data
terbatas yang disokong pada (0,1) dengan kepencongan yang wujud. Model yang
dicadangkan menganggarkan kuantil bersyarat bagi tindak balas teragih Beta
menggunakan rangka kerja teratur Bayesian berhierarki dengan prior pengecutan
global-tempatan. Pensampel Gibbs dibangunkan untuk pengiraan posterior dan
prestasi model dinilai di bawah tahap kepencongan dan senario pencemaran yang
berbeza (5% dan 10% outlier) menggunakan taburan Beta dan logit-normal.
Aplikasi pada set data pengeringan rumpai laut dunia sebenar menunjukkan peningkatan
yang tekal dalam ketepatan ramalan. Merentasi simulasi dan analisis empirik,
BRQBR mengatasi atau memadankan anggaran kemungkinan maksimum (MLE) sambil menunjukkan
keteguhan yang kuat kepada pencilan. Rangka kerja yang dicadangkan menawarkan
penyelesaian yang fleksibel dan tepat untuk memodelkan tindak balas pencong
terbatas.
Kata
kunci: Kepencongan; regresi kuantil bayesian; regresi teguh; taburan beta
RUJUKAN
Abonazel,
M.R., Algamal, Z.Y., Awwad, F.A. & Taha, I.M. 2022. A new two-parameter estimator
for Beta regression model: Method, simulation, and application. Frontiers in
Applied Mathematics and
Statistics 7: 780322. https://doi.org/10.3389/fams.2021.780322
Akram,
M.N., Amin, M., Elhassanein, A. & Ullah, M.A. 2022. A new modified
ridge-type estimator for the beta regression model: Simulation and application. AIMS Math. 7(1): 1035-1057. doi:10.3934/math.2022062
Bishop,
C.M. 2006. Pattern Recognition and Machine Learning (Information Science and
Statistics). Berlin. Heidelberg. Germany: Springer-Verlag.
Bourguignon, M., Gallardo, D.I. & Saulo, H. 2024. Parametric quantile beta regression
model. International Statistical Review 92(1): 106-129. https://doi.org/10.1111/insr.12564
Carvalho,
C.M., Polson, N.G. & Scott, J.G. 2010. The horseshoe estimator for sparse signals.
Biometrika 97(2): 465-480. https://doi.org/10.1093/biomet/asq017
Espinheira, P.L., Ferrari, S.L.
& Cribari-Neto, F. 2008. On Beta regression residuals. Journal of Applied
Statistics 35(4): 407-419. https://doi.org/10.1080/02664760701834931
Ferrari, S. & Cribari-Neto, F.
2004. Beta regression for modelling rates and proportions. Journal of Applied
Statistics 31(7): 799-815. https://doi.org/10.1080/0266476042000214501
Ferrari,
S.L., Espinheira, P.L. & Cribari-Neto, F. 2011. Diagnostic tools in Beta
regression with varying dispersion. Statistica Neerlandica 65(3): 337-351. https://doi.org/10.1111/j.1467-9574.2011.00488.x
Gelman, A., Carlin, J.B., Stern, H.S., Dunson, D.B.,
Vehtari, A. & Rubin, D.B. 2013. Bayesian Data Analysis. 3rd ed. Boca
Raton: CRC Press. https://doi.org/10.1201/b16018
Gianola, D., Cecchinato, A., Naya,
H. & Schön, C.C. 2018. Prediction of complex traits: Robust alternatives to
best linear unbiased prediction. Front. Genet. 9: 195. https://doi.org/10.3389/fgene.2018.00195
Karlsson, P., Månsson,
K. & Kibria, B.G. 2020. A liu estimator for the beta regression model and
its application to chemical data. Journal of Chemometrics 34(10): e3300. https://doi.org/10.1002/cem.3300
Koenker,
R. & Bassett, G. 1978. Regression quantiles. Econometrica 46(1): 33-50. https://doi.org/10.2307/1913643
Li,
Q., Xi, R. & Lin, N. 2010. Bayesian regularized quantile regression. Bayesian
Analysis 5(3): 533-556. https://doi.org/10.1214/10-ba52
McElreath,
R. 2020. Statistical Rethinking: A Bayesian Course with Examples in R and
Stan. 2nd ed. Boca Raton:
CRC Press. https://doi.org/10.1201/9780429029608
Montesinos‑López,
A., Montesinos‑López, O.A., Villa‑Diharce, E.R., Gianola, D. & Crossa,
J. 2019. A robust Bayesian genome‑based median regression model. Theoretical
and Applied Genetics 132: 1587-1606. https://doi.org/10.1007/s00122-019-03303-6
Mukhtar
Eri Suhaeri, Alimudin, Anam Javaid, Mohd. Tahir Ismail & Majid Khan Majahar
Ali. 2021. Evaluation of
clustering approach with Euclidean and Manhattan distance for outlier
detection. AIP Conference Proceedings 2423: 070025. https://doi.org/10.1063/5.0075570
Nascimento,
M., e Silva, F.F., de Resende, M.D.V., Cruz, C.D., Nascimento, A.C.C., Viana,
J.M.S., Azevedo, C.F. & Barroso, L.M.A. 2017. Regularized quantile
regression applied to genome-enabled prediction of quantitative traits. Genet.
Mol. Res. 16(1): 9538. doi: 10.4238/gmr16019538
Pérez-Rodríguez,
P., Montesinos-López, O.A., Montesinos-López, A. & Crossa, J. 2022.
Bayesian regularized quantile regression: A robust alternative for genome-based
prediction of skewed data. The Crop Journal 8(1): 713-722. https://doi.org/10.1016/j.cj.2020.04.009
Piironen,
J. & Vehtari, A. 2017. On the hyperprior choice for the global shrinkage
parameter in the horseshoe prior. Proceedings of the 20th International
Conference on Artificial Intelligence and Statistics. PMLR 54: 905-913.
Simas,
A.B., Barreto-Souza, W. & Rocha, A.V. 2010. Improved estimators for a
general class of beta regression models. Computational Statistics and Data
Analysis 54(2): 348-366. https://doi.org/10.1016/j.csda.2009.08.017
Smithson,
M. & Verkuilen, J. 2006. A better lemon squeezer? maximum-likelihood
regression with beta-distributed dependent variables. Psychological Methods 11(1):
54-71. https://doi.org/10.1037/1082-989X.11.1.54
Tsionas,
E.G. 2003. Bayesian quantile inference. Journal of Statistical Computation
and Simulation 73(9): 659-674. https://doi.org/10.1080/0094965031000064463
Vehtari, A., Gelman, A., Simpson,
D., Carpenter, B. & Bürkner, P.C. 2021. Rank- normalization, folding, and localization: An
improved R̂ for assessing convergence of MCMC (with discussion). Bayesian Analysis 16(2): 667-718. https://doi.org/10.1214/20-BA1221
Yu,
K. & Moyeed, R.A. 2001. Bayesian quantile regression. Statistics and
Probability Letters 54(4): 437-447. https://doi.org/10.1016/S0167-7152(01)00124-9
*Pengarang untuk
surat-menyurat; email: majidkhanmajaharali@usm.my