台灣白米批發與零售市場之不對稱價格傳遞

The Asymmetric Price Transmission on Milled Rice of Wholesale and Retail Market in Taiwan

台灣白米價格的起伏往往波及消費者與生產者的福利及利潤。本研究應用門檻共整合模型，探討台灣白米市場在批發與零售過程的價格傳遞機制。利用2006 年1 月到2012 年6 月各縣市白米價格週資料，本研究發現零售價格與批發價格之間存在顯著之不對稱門檻共整合關係。另依據一致性的門檻估計值，將研究樣本區分為 “高” 及“低” 零售利潤等兩個狀態，結果顯示多數地區在低利潤時期零售價格會較迅速且大幅地反應批發成本的變動，但反之，在高利潤時期批發成本變動並不會明顯傳遞至零售價格。這現象說明利潤的高低是零售業者能否維繫彼此間勾結訂價的關鍵，也佐證不完全競爭市場因素可能是影響現階段台灣白米零售價格調整的原因。不過，藉由比較各地區零售價格之不對稱門檻修正過程與不同利潤狀態下零售價格對批發成本衝擊之反應，本研究也發現白米價格之特殊調整型態其實是受到不完全競爭因素和政府干預力量的交互作用所致。

Rice price fluctuation always impacts on the welfare of consumersand the profit of producers in Taiwan. In this study, it uses the thresholdcointegration model to explore price transmission mechanism on milledrice of wholesale and retail market in Taiwan. Using weekly milled riceprice data by county, its period is from January 2006 to June 2012. Thisstudy finds that it has an asymmetric threshold cointegration relationshipon the milled rice of wholesale and retail price. To separate sample datainto high profit and low profit at retail market by consistent thresholdvalue, it shows that retail price will response rapidly and greatly to reflectthe cost of wholesale changes when the profit of retailer is relative low onretail price. Conversely, the cost of wholesale changes will not transmit toretail price significantly when the profit of retailer is relative high on retailprice. It leads to a relatively stick on price. This phenomenon shows thatlevel of profit is a key factor to maintain price collusion each other amongretailers. It also indicates that imperfect competitive market is a mainreason to impact on the retail price adjustment of milled rice at currentstage. By comparing processes of asymmetric threshold adjustment andthe responses of wholesale price shocks in high and low profit period inTaiwan, this study also found that the particular adjustments of milled riceprice are affected by the government invention.