「石油」在歷經兩次能源危機後，已成為必要之經濟與戰略物資，近年來其高需求、高產量、高油價的現象更對國內之經濟民生造成巨大之影響。目前國內之油品主要由中油、台塑石化所供應，值此非常時期，兩大業者之因應策略更顯重要。故本研究希望透過事件研究以了解兩者因價格策略之歧異對公司營運所帶來之影響，並利用近幾年兩家公司之調價資料以無母數檢定方法分析其競價行為。
綜合實證結果，本研究發現中油在2005 年8 月30 號以價格不變之策略回應台塑石化油價無預警之調漲並沒有造成汽柴油總銷售量之增加；而台塑石化採用相對高價之結果則如預期所料，其汽柴油的總銷售量有下降之趨勢。配合稅後淨利、淨值報酬、營業成本及營業利益之實證結果，可看出中油於總銷售量不變的情況下，其營運狀況有轉劣的跡象；台塑石化則於總銷售量減少的情形下，營運狀況反而轉好，若深究其原因，可能由於其當時適時擴張了外銷市場，然而此說法仍需要更詳細之內外銷資料進行證實。關於兩家業者之競價行為，本研究無法以選定之兩項寡占市場策略行為解釋無鉛汽油之價格訂定；然而透過Wilcoxon 符號等級檢定，其結果則發現 98無鉛汽油之定價上似乎存在著削價競爭之現象。

After experienced two energy crises, the shock of oil price volatility has become more and more critical economically and strategically. In recent years, the phenomena of high demand, high oil production, and high price of oil have resulted in significant impact on economy and people’s welfare in Taiwan. Two major suppliers are Chinese Petroleum Corporation (CPC) and Formosa Petrochemical Corporation (FPC) in Taiwan. Their responsive strategy become more challenging. To discuss this subject deeply, the event study is applied to understand how the differential price strategy influences their operation. Besides, the non-parametric method is also used to analyze the behavior of the competitive price.
Empirical results indicate that after taking the measure of remaining price constant, total sales volume of CPC doesn’t increase. In the other hand, total demand of FPC decreases as expected after increasing price. The results also show that CPC’s operation becomes poorer, and FPC’s operation becomes better. The reason behind FPC’s success may be by expanding foreign market timely. However, the statement needs more data to prove it. Finally, two chosen strategic behaviors can’t explain the price setting of unleaded gasoline, but Bertrand’s statement may explain the phenomenon of price-cutting in 98 unleaded gasoline.

第一章 序論...............................................1
第一節 研究動機及目的.................................1
第二節 研究架構及流程.................................2

第二章 文獻回顧...........................................5
第一節 寡占理論說明...................................5
第二節 寡占市場之策略行為研究相關文獻.................6
第三節 能源研究與事件研究法相關文獻...................8

第三章 資料來源及研究方法................................11
第一節 樣本資料來源及期間............................11
第二節 研究方法......................................12

第四章 實證結果及分析....................................18
第一節 事件研究......................................18
第二節 競價行為分析..................................21

第五章 結論與建議........................................24
第一節 結論..........................................24
第二節 研究限制與未來方向............................25
參考文獻.................................................26

附錄.....................................................30
附表、圖..............................................30
輔助方法............................................. 39

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