限量保價收購制度對稻農預期價格之影響

The Impact of the Limited Guaranteed Price Purchasing on Rice Farmers’ Price Expectation

本研究之主要目的在於探討現行價格政策與農民預期價格間之關連，而本文之主要貢獻在於結合與稻米價格相關之資訊，建立稻農預期價格形成模式，作為其後生產決策之分析基礎。不同於以往以市場均衡（失衡）觀點切入之分析模式，在分析方式上以機率論為主體，限量保證價格收購措施之影響將反映於價格之機率分配上，由於限量收購不同於無限量收購，為避免失之偏頗，進一步結合無干預下之價格分配以及因無限量收購所產生之截斷類型價格分配，按量子力學混成軌域之概念，提出混成價格分配之假說，並於實證分析印證之。結果顯示常態價格分配對於實際價格分配已能有效近似，但以多價格混成分配之價格分配最接近臺灣稻穀躉售價格之分配，此外亦證實限量保證價格措施對稻穀躉售價格分配造成兩種效果：1）改變原有分配之期望值與變異數，即改變市場價格分配，亦即對政府無干預之價格分配造成母體參數變動之效果；2）對於母體參數變動後所產生之新價格分配產生截斷效果。因此按照價格政策研究著眼點之不同，提出三種可行之方案，若分析上有其限制或僅需稻農預期價格之概略值，可採用較簡易之常態價格分配近似。若探討之重點在於現階段價格政策對於稻米產業之影響評估，為研究之精確性，則宜用多價格混成分配作為價格政策與農民預期價格形成間之橋樑。 The purpose of this article is to investigate the impact of the limited quantity guaranteed purchasing on rice farmers’ price expectation. In this article, the price has been treated as a random variable. Its probability distribution function will also be explored under the policy of limited quantity guaranteed purchasing. Since a pure truncated model is not a commendable approach, a hybrid distribution model was first introduced to analyze the price distribution under the current price policy. Three kinds of price expectation models are used to approximate the rice price distribution. Adopting the K-S test, the results show that the multiple hybrid model is more satisfactory to approximate the rice price distribution. The estimation results also suggest that limited quantity guaranteed purchasing causes two effects: 1) shifting the parameters of non-intervention price distribution and, therefore, creating a new distribution; 2) truncating the new price distribution.