Affiliations: Indian Agricultural Statistics Research Institute, New Delhi, India
Correspondence:
[*]
Corresponding author: Ranjit Kumar Paul, Indian Agricultural Statistics Research Institute, New Delhi-110012, India. E-mail: [email protected]
Abstract: Time series with long memory or long-range dependence occurs frequently in
agricultural commodity prices. For describing long memory, fractional
integration is considered. The autoregressive fractionally integrated
moving-average (ARFIMA) model along with its different estimation procedures
is investigated. For the present investigation, the daily spot prices of
mustard in Mumbai market are used. Autocorrelation (ACF) and partial
autocorrelation (PACF) functions showed a slow hyperbolic decay indicating
the presence of long memory. On the basis of minimum AIC values, the best
model is identified for each series. Evaluation of forecasting is carried
out with root mean squares prediction error (RMSPE), mean absolute
prediction error (MAPE) and relative mean absolute prediction error (RMAPE).
The residuals of the fitted models were used for diagnostic checking. Long
memory parameter of ARFIMA model is computed by Geweke and Porter-Hudak
(GPH), Gaussian semiparametric and wavelet method by using Maximal overlap
discrete wavelet transform (MODWT). To this end, a comparison in
the performance of different estimation procedures is carried out by Monte
Carlo simulation technique. The R software package has been used for data
analysis.
Keywords: Long memory, ARFIMA, spot price of mustard, Monte Carlo simulation