Modeling Red Bird’s Eye Chili Prices in West Java with Calendar Variation Effects
Keywords:
ARIMAX, GARCH, Red Bird’s Eye Chili, Calendar Variations, VolatilityAbstract
Red bird’s eye chili is one of Indonesia’s strategic horticultural commodities, playing a crucial role in household consumption and food inflation stability. Price fluctuations of red bird’s eye chili frequently occur due to changes in supply, distribution, climatic conditions, and increased demand during major religious holidays. West Java Province is the most populous region and has a high demand for red bird’s eye chili, while its production is relatively lower compared to major production centers. These conditions result in high price volatility for red bird’s eye chili in West Java. This study aims to model red bird’s eye chili prices in West Java by considering the effects of calendar variations and price volatility. The data used consists of weekly red bird’s eye chili price data from January 2020 to August 2025 sourced from the Strategic Food Price Information Center (PIHPS). The method used is the ARIMAX model with exogenous variables in the form of religious holiday dummies such as Eid al-Fitr, Eid al-Adha, and Christmas, combined with the GARCH model to model price volatility. The results show that the best model is ARIMAX(2,1,1)-GARCH(1,1). The Eid al-Fitr and Christmas dummy variables have a significant effect on price changes. Forecast accuracy evaluation yielded an MAPE value of 22.71%, indicating that the model has fairly good forecasting capability for data on volatile commodities. The ARIMAX-GARCH model obtained is capable of describing the dynamics of price changes as well as the price volatility of red bird’s eye chili in West Java.
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