異質商品動態特徵價格之研究──以黃豆及其製品為例

Heterogeneous Commodity and Dynamic Hedonic Pricing: Soybeans and their Products

Chavas 與 Kim (2005) 的動態特徵訂價（Hedonic Pricing）模型證明了異質商品的特徵價格與商品價格間的共整合連動關係具有一致性。本研究將該模型應用於台灣的黃豆、黃豆油與黃豆粉三項異質商品，並分析此三項商品的價格是否充分反應其特徵成分及價格間是否存在長期連動關係。台灣黃豆消費量有95%以上為進口，國際市場依賴度很深，而多數進口之黃豆是以加工為主，由於黃豆品質影響加工後產品之品質，故黃豆、黃豆油及黃豆粉三者之價格關係是否存在某種關聯性值得關切；另外，2006 年10 月至2008 年中期，國際大宗穀物價格創新高，亦造成國內加工原物料成本高漲，黃豆油及豆粉價格之合理性受到質疑，為探討黃豆製品在這波穀物價格高漲下，黃豆、黃豆油與黃豆粉三項異質商品價格是否充分反映其組成成分價值，而各價格間是否存在長期關係亦值得探討。研究結果顯示，根據特徵價格理論推導而得之特徵價格向量與利用Johansen 共整合所求得之黃豆及其製品價格長期變動之共整合向量相近，顯見台灣之黃豆、黃豆油與黃豆粉之價格長期關係符合特徵價格之訂價特性。

With overwhelming proportion of imported soybeans is used to beprocessed by factories, we introduce the hedonic pricing model withdynamics consideration proposed by Chavas and Kim (2005) to find outthe long-term price relationship among three differentiated products:soybeans, soybean oil and soybean meal.The empirical result reflects that the pricing of Taiwanese soybeanindustry agrees with the hedonic pricing model, in the long-run at least,given the assumption of fixed composition of the differentiatedcommodities. Since the cointegrated price vector under hedonic pricingmodel matches closely to that under Johansen cointegration approach, itpoints out that the long-term price relationship among soybeans, soybeanoil and soybean meal is consistent with hedonic pricing model.