Study of X-13 ARIMA SEATS Modeling for Rice Price Index Data in Indonesia

Outlier on a data can cause several problems, including a model that is formed to produce a large residual, and the variance of data will increase. A robust method for outlier problems is needed in order to produce an unbiased model. X-13 ARIMA SEATS is one of robust method in time series. X-13 ARIMA SEATS is a seasonal adjustment method capable of detecting, resolving the presence of outliers, and overcoming seasonal and calendar effect. The X-13 ARIMA SEATS consists of two stages that is using regARIMA model, and using X-12 seasonal adjustment. In this paper, X-13 ARIMA SEATS method is compared with ARIMA method to prove its ability to overcome outliers based on the smallest error value. In this paper, the X-13 ARIMA SEATS method is applied to model and forecast the rice price index in Indonesia in January 2010-December 2018. The results showed that the X-13 ARIMA SEATS method produces a model with smaller MAPE and RMSE values than the ARIMA model.