目標區與農產品價格之穩定：農產品現貨與期貨模型

Target Zones and Stabilization of Commodity Prices: Agricultural Spot and Futures Prices

一國的物價高低，攸關著國民生計，如何利用有限的資源及政策來穩定物價，除了是政府關注的議題外，亦是人民所關心的焦點。另外，有鑑於目前農產品之期貨交易日益活絡，且農產品現貨價格的變化與期貨價格之變化互有牽連，因此本文將延伸Frankel (1986)、Lai、Hu 與Wang(1996)、賴景昌、王葳與胡士文(2000)、及呂麗蓉等(2008) 等之經濟模型，據以探討若政府對農產品設定了現貨價格目標區，是否可達到農產品現貨價格有安定之作用，農產品期貨價格、非農產品價格（或匯率）是否會因此而付出不安定之代價。本文發現：當經濟體系出現干擾時，政府若設立農產品現貨價格目標區，農產品現貨價格是否存在蜜月效果取決於農產品的「現貨價格效果」與「期貨投機程度」之相對大小；而農產品期貨價格則會更進一步受到農產品「資產的需求程度」相對大小影響。此外，政府在追求社會福利損失極小化的前提下，不管農產品現貨價格是否存在蜜月效果，未必就應該實施農產品現貨價格目標區，而是視政府整體社會最適化之考量而定。

The stability of price level is the question which is cared deeply aboutby the economy. In addition, an increasing in transactions of agriculturalfutures price and reacting between agricultural spot and futures prices,this paper extend the model of Frankel (1986), Lai, Hu, and Wang (1996),Lai, Wang, and Hu (2000), and Lu et al. (2008) and investigate if ahoneymoon effect as described in Krugman (1991) exists after the targetzones policy was announced. On the positive side, it is found thatwhether the honeymoon effect exists depending on the relativemagnitude between the spot price effect and the degree of speculation inrelation to the agricultural product. Moreover, not only are the abovecondition able to influence the stability of the agricultural futures price, butalso the relative magnitude between the degree of asset demand and thedegree of speculation, and the relationship between agricultural spot andfutures prices. Finally, an announcement of an agricultural spot pricetarget zone will stabilize manufactured product prices regardless of theprevailing situation. In the normative side, it is found that honeymooneffect is not the main reason to affect the government to defend theagricultural spot price target zone under social welfare loss-minimizing.