同步同幅調價－“聯合行爲”或“平行行爲”?

在歷經20次「同步、同幅」調整公告牌價後，公平會於2004年10月認定中油和台塑，以事先、公開方式傳遞調價資訊，違反公交法中聯合行爲規定。本文透過電訪資料，驗證「同步、同幅」調價，是否如處分書中所推論般，導致售予下游加油站的批售價格一致。雖說批售價格爲業務機密，但台灣大多數加油站採用折讓促銷（包括現金和贈品）。這些價差反映油品買入（批售價格）和賣出（公告牌價）間利差，在兩業者牌價相同下，可視爲批售價格替代變數。在控制各加油站所在區位，加盟型態，市場競爭，油品需求後，我們發現中油折讓明顯低於台塑約1-2%，顯示中油和台塑的批售價格並不相同，這結果即使在控制加油站油品（中油、台塑）內生性後仍成立，顯示處分書推論可能有誤。

關鍵字

聯合行爲；促進行爲；平行行爲；油品市場

並列摘要

In Oct, 2004, after 20 ”simultaneous price adjustments of the same scale” of the suggested retail price (SRP), the Fair Trade Committee (FTC) found that the Chinese Petroleum Company (CPC) and Formosa Petrochemical Company (FPCC) had violated the provision against ”concerted action” because these two refineries communicated price information through the media. This paper attempts to use survey data of downstream gas stations to examine whether ”simultaneous price adjustments of the same scale” of the SRP, as implied by the FTC's indictment, actually result in the identical factory invoice price (FIP). Although obtaining FIP is difficult, the majority of gas stations in Taiwan provide sales discounts, either cash rebates or gifts. Because the discount is due to the difference between FIP and SRP, it can be used as a proxy for FIP conditional on the same SRP. After controlling for a gas station’s location and ownership, nearby gas demand, and local competition, our results show that the discount is larger for stations selling FPCC gas, indicating unequal FIP between the two refineries. This result holds after accounting for the fact that stations endogenously select upstream suppliers. Our finding is inconsistent with the statements in the FTC indictment.