國際原物料價格與散裝海運運價指數之連動及其對運價指數預測之影響

The Co-movement of Raw Material Prices and Dry-Bulk Shipping Rate Indices and Its Effect on Freight Rate Index Forecasts

乾散裝海運於國際原物料之貿易上扮演了重要的角色。由於國際原物料價格的變動相當程度反映了供需的變化，而其供需的變化也直接影響了對海運之需求，並進而影響到海運運價，原物料價格與海運運價指數必存在某種連動及關聯。本文主要係基於此一考量，先以Johansen共整合檢定驗證原物料價格與散裝海運運價指數間是否存在著長期均衡之連動關係，當均衡關係存在時，接著再以向量誤差修正模型（VECM），探討原物料價格與運價指數間的互動關係。實證結果發現，運價指數之季節性因素在此並不顯著，此外，前期原物料價格會影響後期運價指數。至於依據原物料價格與運價指數間之互動關係所進行運價指數未來走勢預測之結果，顯示運價指數之預測值與實際值之發展方向大致相同，其中又以BPI之預測更為準確，表示原物料價格對海運運價指數會有一定之影響。

Dry-bulk shipping plays a major role in moving raw materials internationally. Since the movement of the prices of raw materials shipped reflects, to a certain degree, the interactions between demand and supply for those materials which in turn impact the demand for dry-bulk shipping and freight rates, it should have a close relationship with the changes of dry-bulk shipping freight indices. Based on this argument, this paper first examines the long-term equilibrium relationships between raw material prices and dry-bulk shipping freight indices by Johansen cointegration test. With the existence of long-term equilibrium relationship, the interacting relationships between the movement of raw material prices and dry-bulk shipping freight indices are further explored by Vector Error Correct Models (VECM). The results indicated that seasonality is not significant in dry-bulk shipping freight indices. In addition, raw material prices move ahead of dry-bulk shipping freight indices. Finally, forecasts on future movements of shipping freight indices taking into account the relationship established, proved to be quite satisfactory, especially for BPI indices, indicating that the inclusion of price information of raw materials does improve the forecasting accuracy.