台灣是個高?仰賴能源進口之國家，對原油進口依存?接近 100%，近?國際油價大幅上漲，這種全球性石油衝擊效應（Oil Shock），使得國內油價跟著調漲而衝擊到?用汽油消費者；然而，國內油品市場雙?頭中油及台塑，其調價?為是否與原油價格同步，係社會大眾所極?關注之議題；故本文擬剖析國內外油價漲跌訊息，並進一步檢證國內油品價格是否呈現漲多跌少及?供油商之?合調價之?對稱議題。 本文?用 2000 ? 12 月 31 日至 2006 ? 12 月 31 日共 313 筆週資?，首先?用五種敘述統計公式，檢證國際原油價格、國內中油及台塑之汽油及柴油批發價格、國內汽油及柴油?售價格，其漲跌幅是否存在漲多跌少與向下僵固性之?對稱現象；其次?用單根檢定法，檢測各油價變?為 I(1)之非平穩??下，建構 95汽油、柴油市場?對稱誤差修正模型（Asymmetric Error-Correction Model），推估長期漲跌誤差修正係?，據以判定國際油價之漲跌，對國內各油價變?是否具有漲跌?對稱問題，?進一步?用因果關係探究國內?大供由商?合調整油價之?對稱現象。 實證研究結果發現：(1) 由漲跌次?及漲跌幅?看，國內外各種油價變?皆出現漲多跌少之?對稱現象。(2) 國際油價與國內批發、?售油價具有長期共整合關係。(3) 由長期?對稱誤差修正模型觀之，?以 WTI 為調價指標，國內?用95 汽油?售價呈現漲幅大於跌幅之?對稱現象；?以 70%杜拜＋30%布?特為調價指標，國內汽油?售價則呈現跌幅大於漲幅之?對稱現象；此項訊息透?，以 WTI 為國際油價指標，長期下漲跌誤差修正之波動差距，比 D7B3 ?得大，亦即同樣是面對國際油價上漲，國內油品價格調漲幅?大於調跌幅?之?對稱現象，WTI 比 D7B3 ?明顯。(4) 經由總衝擊係?檢定得知，國際原油價格單向影響國內各油價；中油及台塑批發價之調整呈現互為因果之?合調價?為。(5) 歸納本文實證結果，發現國內外油品本身皆存在漲多跌少之?對稱現象，且發現以WTI 作為國際油價指標，將高估對國內汽油?售價之衝擊而有欺瞞消費者之疑；而國內?油品雙占廠商之油價調整，呈現互為因果之?合?為。 Taiwan is highly dependent on import in amounts of energy, especially the crude oil. In recent years, the crude oil price keeps rising fiercely, causing a serious impact on domestic oil prices and economy. The Chinese Petroleum Corp.(CPC) and Formosa Petrochemical Corp.(FPCC) make up the entire gasoline market in Taiwan. In this context, whether the domestic gasoline wholesales prices and retail prices adjust in the same pace with the crude oil prices is the main subject that the research tried to identify. The research applies Asymmetric Error Correction Model to examine for the issue of asymmetries in the transmission of shocks to crude oil prices onto the wholesale and retail gasoline prices, using weekly data for period January 2001 to December 2006. The results show that there are more rises than falls in frequencies and rate in international and domestic oil market. Moreover the long-term cointegrating relation exists between crude oil price and domestic wholesale and retail prices. Additionally, we find evidence of gasoline price asymmetries if we adopt WTI as the indicator in floating oil pricing mechanism. As a result, we may overestimate the response of domestic gasoline price to the oil shock. At last, the retail gasoline price is affected by international oil price and wholesale gasoline price. In duopoly gasoline wholesale market, the pricing strategy of CPC&FPCC both firms are cooperative.
