農產品市場干擾與商品價格之動態調整：體制崩潰之應用

Agricultural Market Disturbances and the Dynamic Adjustment of the Commodity Prices: Application of Regime Collapse

本文以Frankel (1986)及Lai, Hu and Wang (1996)之理論架構為基礎，建立涵蓋農產品與製造業產品（或非農產品）兩部門的封閉經濟體系模型，據以探討：以農產品市場干擾導致農產品價格波動為因，政府穩定農產品價格為果，搭配體制崩潰的題材，分析農產品價格、製造業產品價格以及政府對農產品購買量的動態走勢。經由本文之分析可知，當政府所訂定之農產品價格的門檻水準高於未設門檻之新均衡水準時，農產品市場出現干擾致使供給大增之際，原為自由浮動的農產品價格體制會瞬間崩潰為固定門檻的農產品價格體制，政府因應地調高農產品的購買量。然若政府所訂定之農產品價格的門檻水準低於未設門檻之新均衡水準時，農產品市場出現干擾後，農產品價格將持續下跌，政府為穩定農產品價格而設置農產品價格下限門檻的措施，反而造成最終農產品價格水準的跌幅較不干預時為高，亦即助長了價格的不穩定。

According to the theoretical frameworks of Fankel (1986) and Lai, Huand Wang (1996), we set up a closed economy model including twosectors of agricultural and manufactured products. When there is adisturbance in the agricultural market and the government tries tostabilize agricultural prices above the minimum price that was set by thegovernment, we analyze the dynamic process of agricultural prices,manufactured prices and purchase amount of the government foragricultural products.We find that when the initial threshold of agricultural prices is higherthan the new equilibrium level, the price regime of agricultural productswill collapse instantaneously from being flexible to being regulatedbecause of the increase in supply of agricultural products caused bydisturbance of agricultural market. Meanwhile, the government will raisepurchase amount for agricultural products to keep agricultural pricesequal to the threshold level. But if the initial threshold of agriculturalprices is lower than the new equilibrium level, agricultural prices willcontinuously decrease and be more unstable comparing to the situationthat government did nothing about agricultural prices.