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Sensitivity of Bayesian Truncated Spline Regression to Prior and Knot Configuration in Stunting Models Zahra, Septi Nafisa Ulluya; Fernandes, Adji Ahmad Rinaldo; Efendi, Achmad; Solimun, Solimun; Nasywa, Alfiyah Hanun; Junianto, Fachira Haneinanda
CAUCHY: Jurnal Matematika Murni dan Aplikasi Vol 10, No 2 (2025): CAUCHY: JURNAL MATEMATIKA MURNI DAN APLIKASI
Publisher : Mathematics Department, Universitas Islam Negeri Maulana Malik Ibrahim Malang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18860/cauchy.v10i2.37381

Abstract

This study develops a Bayesian bi-response regression model using a truncated spline approach to examine nonlinear effects of economic, dietary, and environmental factors on nutritional and physical stunting. Sensitivity analysis was conducted to evaluate the influence of prior types and knot numbers on model performance using Deviance Information Criterion (DIC), Root Mean Square Error (RMSE), and bias. Results show that the informative Normal–Gamma prior combination yields the best performance, with the lowest DIC, smallest RMSE, and minimal bias. Models with three knots provide higher predictive accuracy, while noninformative Uniform priors cause instability and overfitting. Overall, the findings indicate that prior specification has a stronger effect on model robustness than the number of knots, emphasizing the importance of informative priors in Bayesian spline modeling for understanding complex, nonlinear determinants of child stunting.
Modified Ramsey RESET in Combined Truncated Spline–Fourier Nonparametric Path Analysis on Waste Management Behavior Hidayatulloh, Moh Zhafran; Solimun, Solimun; Fernandes, Adji Achmad Rinaldo; Rizqia, Anggun Fadhila; Junianto, Fachira Haneinanda
CAUCHY: Jurnal Matematika Murni dan Aplikasi Vol 10, No 2 (2025): CAUCHY: JURNAL MATEMATIKA MURNI DAN APLIKASI
Publisher : Mathematics Department, Universitas Islam Negeri Maulana Malik Ibrahim Malang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18860/cauchy.v10i2.37239

Abstract

Nonparametric path analysis is a statistical approach that does not require the functional form of relationships between variables to be known a priori. Classical path analysis assumes linearity, which can be tested using the Ramsey Regression Specification Error Test (RESET). If the linearity test indicates that the relationships between variables are nonlinear, a nonparametric model can be applied. The purpose of this study is to develop a modified Ramsey RESET to identify nonparametric relationships modeled using truncated spline and Fourier series. The modified Ramsey RESET algorithm was successfully implemented to detect the optimal functional form of the nonparametric truncated spline and Fourier series and was subsequently applied to behavioral data on waste management practices. Furthermore, this study proposes an estimator for a hybrid nonparametric path model combining truncated spline and Fourier series approaches. The analysis results reveal that the best model integrates truncated spline with one and two knot points and a Fourier series with one oscillation. The model achieved an adjusted coefficient of determination of 0.956, indicating that it explains 95.6% of the variation in the Behavior of Transforming Waste into Economic Value, while the remaining 4.4% is explained by other unobserved factors outside the model.
Nonparametric Path Modeling with Double Resampling for Waste Economic Value Utilization: Simulation-Based Performance Comparison Hidayat, Kamelia; Fernandes, Adji Achmad Rinaldo; Iriany, Atiek; Solimun, Solimun; Hidayatulloh, Moh. Zhafran; Junianto, Fachira Haneinanda
CAUCHY: Jurnal Matematika Murni dan Aplikasi Vol 10, No 2 (2025): CAUCHY: JURNAL MATEMATIKA MURNI DAN APLIKASI
Publisher : Mathematics Department, Universitas Islam Negeri Maulana Malik Ibrahim Malang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18860/cauchy.v10i2.37218

Abstract

Waste generation exceeding landfill capacity highlights the urgency of realizing its economic value. This study analyzes the effect of Quality of Facilities and Infrastructure (X1) and Use of Waste Banks (X2) on Waste Management-Based 3R (Y1) and Waste Economic Value Utilization (Y2) using a truncated spline nonparametric path model. This study evaluates the performance of a nonparametric path analysis model based on truncated spline combined with a double resampling. Data were collected using a Likert scale questionnaire on community perceptions of waste’s economic benefits in Batu City. Simulation results show that the Jackknife-Bootstrap method achieves the lowest average bias (0.058), outperforming single resampling approaches such as Single-Bootstrap (0.178) and Single-Jackknife (0.176). Empirical findings indicate that improvements in the Quality of Facilities and Infrastructure  (X1) and Waste Bank Use (X2) significantly enhance Waste Management Based 3R (Y1) and Utilization of Waste Economic Value (Y2). The truncated spline model reveals a saturation effect, where the marginal benefits of X1 and X2 decrease beyond a threshold. Furthermore, Y1 positively affects Y2, emphasizing the importance of efficient waste management in enhancing economic value. The results support policies promoting balanced infrastructure development, community empowerment, and institutional innovation for sustainable circular economy implementation.
Development of Multigroup Structural Equation Modeling on Structural and Measurement Models For Waste Management Behavior Patterns Khairani, Aldianur; Solimun, Solimun; Fernandes, Adji Achmad Rinaldo; Junianto, Fachira Haneinanda; Khairina, Nadia
CAUCHY: Jurnal Matematika Murni dan Aplikasi Vol 10, No 2 (2025): CAUCHY: JURNAL MATEMATIKA MURNI DAN APLIKASI
Publisher : Mathematics Department, Universitas Islam Negeri Maulana Malik Ibrahim Malang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18860/cauchy.v10i2.34997

Abstract

This research aims to develop multigroup Structural Equation Modeling (SEM) on structural and measurement models to analyze waste management behavior patterns in Batu City. Secondary data were used from 120 respondents who were grouped into two: Group 1 (away from tourism) and Group 2 (near tourism). Latent variables include environmental quality, waste bank utilization, awareness of the use of 3R, and economic benefits from waste. The analysis was carried out by validity, reliability, linearity (Ramsey RESET), and multigroup SEM. The validity and reliability results showed that all indicators met the criteria (Corrected Item Total Correlation 0.3; Cronbach's Alpha 0.6). The linearity test proves that the relationship between variables is linear. Measurement models using formative indicators showed significant contributions, such as environmental maintenance (Group 1 coefficient: 0.369; Group 2: 0.518) and reuse effectiveness (Group 1 coefficient: 0.555; Group 2: 0.590). In the structural model, environmental quality had a stronger direct effect on 3R awareness in Group 2 (near tourism; coefficient: 0.432), while the use of waste banks had a more effect on Group 1 (away from tourism; coefficient: 0.414). The indirect effects through 3R awareness were also significant, with a total determination coefficient of 0.732, suggesting the model was able to explain 73.2% of the data variance. This study highlights the importance of a location-based approach in waste management policies, particularly the optimization of waste banks in areas far from tourism (Group 1) and the increase of 3R awareness in areas near tourism (Group 2).
Co-Authors Achmad Efendi Agustina, Evi Lusi Al Jauhar, Hafizh Syihabuddin Ali Djamhuri Alim, Viky Iqbal Azizul Amanda, Devi Veda Angga Dwi Mulyanto Arief Rachmansyah Aries Budianto Arini, Luthfia Hanun Yuli Armanu Thoyib Armanu Thoyib Asaliontin, Lisa Atiek Iriany Azizah, Amelia Nur Azizah, Maulida Balqis, Nabila Azarin Bambang Semedi Bambang Subroto Bonifasia Elita Bharanti Budiyanto Budiyanto Candra Dewi Dewi Yanti Liliana Dirman, Eris Nur Djumahir .. Djumilah Hadiwidjojo Djumilah Zain Endang Arisoesilaningsih Endang Setyawati Eni Sumarminingsih Evellin Dewi Lusiana, Evellin Dewi Fernandes, Adji Achmad Rinaldo Fernandes, Adji Ahmad Rinaldo Fimba, Adfi Bio Firman Iswahyudi Mustopo Gultom, Fandi Rezian Pratama Halim .. Hamdan, Rosita Hamdan, Rosita Binti Handoyo, Samingun Hardianti, Rindu Hidayat, Kamelia Hidayatulloh, Moh Zhafran Hidayatulloh, Moh. Zhafran Ida Nur Hidayati Ida Nur Hidayati Istiqomah, Nur Junainto, Fachira Haneinanda Junianto, Fachira Haneinanda Khairani, Aldianur Khairina, Nadia Kurniasari, Lia Loekito Adi Soehono Loekito, Loekito Luthfatul Amaliana, Luthfatul M. Agung Wibowo, M. M.S Idrus Made Subudi Margono S. Margono Setiawan Meilina Retno Hapsari Meirina, Risk Mintarti Rahayu Mitakda, Maria Bernadetha Mudjiono Mudjiono, Mudjiono Muh. Arif Rahman Muh. Arif Rahman Musran Munizu Nasywa, Alfiyah Hanun Ni Wayan Surya Wardhani Ni Wayan Surya Wardhani Nuddin Harahab Nurdin, Muhammad Rafi Hasan Nurjannah Nurjannah Nurjannah Padma Devia, Y. Papalia, M. Fikar Permatasari, Kiky Ariesta Pramaningrum, Dea Saraswati Pratama, Yossy Maynaldi Pusaka, Semerdanta Qomariyatus Sholihah Rahma Fitriani Rahmanda, Lalu Ramzy Rahmi Widyanti Ramadhan, Rangga Ramifidiosa, Lucius Rejeki, Sasi Wilujeng Sri Rinaldo Fernandes, Adji Achmad Rizqia, Anggun Fadhila Rohma, Usriatur Rohman, Muhammad Zainur Rosidi Rosidi Rozy, Agus Fachrur Saputra, Yoyok Yuni Sasongko Budisusetyo Sepriadi, Hanifa Sianipar, Celia Suci Astutik Sumara, Rauzan Sumarminingsih, Eni Surachman .. Theresia Mitakda, Maria Bernadetha ubud sallim Ullah, Mohammad Ohid Ullah, Muhammad Ohid Utama, Risha Ardasari Utomo, Candra Rezzining Wulat Sariro Weni Wayan Firdaus Mahmudy Wayan Sri Kristinayanti Yulianto, Shalsa Amalia Yulvi Zaika Zahra, Septi Nafisa Ulluya Zaki Yamani Zamelina, Armando Jacquis Federal