Sains Ma1aysiana 26(1): 125-132 (1997)                                                                      Pengajian Kuantitatif/

                                                                                                                                                Quantitative Studies

 

Structural Change of Palm Oil Price Data

 

 

Lalang Buana

The Indonesian Oil Palm Research Institute

Dept of Statistics, Faculty of Mathematical Sciences

Universiti Kebangsaan Malaysia

43600 UKM Bangi, Se1angor D.E.

 

Ahmad Mahir Razali & Zainodin Haji Jubok

Jabatan Statistik, Faku1ti Sains Matematik

Universiti Kebangsaan Malaysia

43600 UKM Bangi, Se1angor D.E.

emai1: zainodin@pkrisc.cc.ukm.my

 

 

ABSTRACT

 

The changes on the vegetables oil trading environment might change the foundation of palm oil pricing and induce a structural change to the price model. Failing to take it account the structural change in a data series might lead to misspecification of the actual model. This study, however, showed that structural change was not present in the monthly, January 1983 to July 1995, palm oil price, but it was present on the unconditional variance. The underlying model of this series was ARIMA (3, 1, 0) with ARCH (1). The critical change of the unconditional variance took place in April 1989.

 

ABSTRAK

 

Perubahan dalam suasana perdagangan minyak sayuran boleh mengubah asas harga minyak kelapa sawit. Seterusnya ia merangsang perubahan dalam struktur model harga minyak tersebut. Kegagalan untuk mengambil kira perubahan struktur dalam siri data menjadikan model itu tidak menepati spesifikasi daripada model sebenar. Kajian ini mendapati bahawa perubahan struktur tidak berlaku bagi data harga minyak sawit dari Januari 1983 hingga Julai 1995. Tetapi perubahan berlaku pada varians tidak bersyaratnya. Model asas bagi siri ini adalah ARIMA (3,1,0) dengan ARCH(1). Didapati juga bahawa perubahan yang kritikal bagi varians tidak bersyarat berlaku pada bulan April 1989.

 

 

RUJUKAN/REFERENCES

 

Andrew, D.W.K. 1993. Test for parameter instability and structural change with unknown change point. Econometrica 61(4): 821-856

Box, G. P. and Jenkins, G. M. 1976. Time Series Analysis Forecasting and Control. San Francisco: Holden-Day Inc.

Buana, L. and Daswir. 1993. Potensi pengembangan pasar rninyak kelapa sawit. Berita Pusat Penelitian Kelapa Sawit 21(1): 75:80

Chow, G. 1969. Test of equality between sets of coefficients in two linear regressions. Econometrica 28(3): 591-605

Engle, R. F. 1982. Autoregressive conditional heteroscedasticity with estimates of the variance of United Kingdom inflation. Econometrica 50(4): 987-1007.

Hackl, P. and Westlund A.H. 1989. Statistical analysis of "Structural Change" an annotated bibliography. Empirical Econometrics 14: 167-192.

Howard, B. 1993. Oils & Oilseeds to 1996. The new pattern of supply and demand. The Economist Intelligence Unit. London

Lin, C. J. and Terasvirta. T. 1994. Testing the constancy of regression parameters against continuous structural change. Journal of Econometrics 62: 211-228.

Perron, P. 1989. The great crash, the oil price shock, and the unit root hypothesis. Econometrica 57(6): 1361-1401.

Thomas, R. L. 1993. Introductory Econometrics. London: Longman.

 

 

 

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