Time series analysis of tomato prices in the selected markets of Gujarat

The study examines the time series analysis of tomato prices in the selected markets of Gujarat based on time series data collected from January 2006 to December 2021. Different forecasting models were used for tomato prices in the study. According to the Augmented Dickey-Fuller (ADF) test, the price series of Rajkot, Surat, and Vadodara were stationary at level, while Ahmedabad and Bharuch were non-stationary at level. The presence of four co-integration equations was discovered via Johansen's co-integration test for integration, indicating that markets are in long-run equilibrium. SARIMA, GARCH, and EGARCH models were applied for modelling and forecasting tomato prices. On the basis of least AIC, it was observed that, SARIMA(0,0,3)(0,1,1)12, SARIMA(1,0,0)(1,0,1)12, SARIMA(1,0,0),(0,1,1)12, SARIMA 1,0,0)(1,1,1)12, and SARIMA(0,0,1)(0,1,1)12 models were selected for Ahmedabad, Bharuch, Rajkot, Surat, and Vadodara markets, respectively. There was no scope for GARCH models so EGARCH was tested and models were chosen based on the MAE and MAPE values. The SARIMA model's predicted errors were found to be less than the EGARCH models. As a result, the SARIMA model was proven to be a better model for forecasting tomato prices in all of the market places studied.