Sifriyani, I Nyoman Budiantara, Krishna Purnawan Candra, Syaripuddin, Syatirah Jalaluddin, Mariani Rasjid, Ruslan
This study proposes an advanced spatio-temporal framework to forecast strategic food commodity prices in Indonesia using Geographically and Temporally Weighted Spline Regression (GTWSR), a nonparametric extension of GTWR designed to capture nonlinear spatio temporal effects. Monthly data from the Strategic Food Price Information Center (SFPIC) and Statistics Indonesia (BPS), covering eight key commodities and the Farmer Price Index across 34 provinces (January 2022–August 2024), were analyzed through spatial distance measurement, bandwidth optimization, local parameter estimation, and statistical validation. The GTWSR model demonstrated strong predictive performance (overall accuracy: R² = 91.61 %, RMSE = 1.22, MAE = 0.94, MAPE = 3.7 %), with rice and garlic achieving the highest accuracy, while red and cayenne chili showed greater errors due to price volatility. Spatial disparities were evident, as eastern provinces such as Papua, Maluku, and East Nusa Tenggara consistently faced higher prices compared to western regions. These findings underscore the need for region-specific interventions to strengthen logistics and stabilize horticultural supply chains. Limitations include reliance on monthly aggregated data, the temporal scope ending in 2024, and dependence on secondary datasets, which may affect replication and long-term applicability. © 2025 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license. http://creativecommons.org/licenses/by-nc-nd/4.0/
Study Program of Statistics, Department of Mathematics, Faculty of Mathematics and Natural Sciences, Mulawarman University, Samarinda, 75119, Indonesia; Department of Statistics, Faculty of Science and Data Analytics, Institut Teknologi Sepuluh Nopember, Surabaya, 60111, Indonesia; Department of Agriculture, Faculty of Wet Tropical Agriculture, Mulawarman University, Samarinda, 75119, Indonesia; Study Program of Mathematics, Department of Mathematics, Faculty of Mathematics and Natural Sciences, Mulawarman University, Samarinda, 75119, Indonesia; School of Medicine, Faculty of Medicine and Health Sciences, Universitas Islam Negeri Alauddin Makassar, Makassar, 92113, Indonesia; Department of Pulmonology, Faculty of Medicine, Bosowa University, Makassar, 90231, Indonesia; Faculty of Sport Science and Health, State University of Makassar, Makassar, 87131, Indonesia
