市場整合與單一價格法則的檢測：以吳郭魚市場為例

本研究應用共整合分析（cointegration methods）探討臺灣吳郭魚條凍全魚與國際市場的互動關係，並測試各國價格之間的市場整合和價格動態。從臺灣吳郭魚條凍全魚的消費批發市場、出口市場的供應鏈的縱向角度，觀察與美國條凍全魚進口及中國條凍全魚出口價格間的短期變動調整及長期均衡關係，並檢測市場的單一價格法則（law of one price, LOP）及價格的弱外生性（weak exogeneity）。結果顯示，美國吳郭魚全魚條凍進口價格、中國出口價格、臺灣出口價格及消費批發市場價格間具有長期均衡關係。美國進口及中國出口價格具弱外生性，顯示其短期對長期均衡的調整幅度並不明顯，為市場長期均衡價格的領導者。美國進口價格、臺灣出口價格及臺灣消費的批發市場價格符合單一價格法則，隱含臺灣與美國吳郭魚市場的相對價格為常數，市場價格的變動將完整在臺灣批發、出口及美國進口市場間傳遞。不論長期價格趨勢或短期價格調整，臺灣批發、出口及美國進口、中國出口價格間有顯著的連接性，因此，國內相關政策決策單位在思維產業調整與發展策略時，應從經濟角度出發，國際競爭市場因素不能被忽略。 In this paper the price dynamics and the degree of market integration in the Tilapia whole fish market is examined using cointegration methods. The study focuses on Taiwan wholesale price and export price, China export price and United States import price of Tilapia whole fish market. The price co-movements in these markets, their short term price adjustment and long run cointegrated, were evaluated. In this study, both Taiwan export market and the wholesale market price reactions are distinguished. Evidence of market integration is found for all four market prices; on the test of exogeneity, the US import and China export is the market leaders and so determine the market long run prices. The evidence of prices uniformity i.e., the acceptance of law of one price (LOP), holds among Taiwan wholesale, Taiwan export and US import markets implies that relative prices are constant and hence, the price changes would perfectly transmit among these markets. Thus, alternative management and development strategies should consider competing markets from an economic respective.