タイ米輸出制度の経済理論的分析

Abstract

The factors which complicate the rice export system in Thailand are as follows : (1) Both private and government exports occur. (2) Three kinds of export duties are levied on private rice exports, i. e., i) rice export premium (specific duty), ii) rice export tax (ad valorem), iii) local tax on rice export (specific duty). (3) Export quota are assigned to private rice exporters. (4) A "reserve stock policy" is executed : Private exporters are required to sell quantities of rice to the government agency which are equivalent to a certain proportion to their rice exports at prices generally lower than their purchasing prices. The government in turn sells rice out of the reserve stock at prices lower than corresponding market prices as circumstances require. In this paper the author refer to this policy as "export-linked low-price selling." In this paper diagrams are mainly used, and an enphasis is placed on the analysis of the case when both single amalgamated "rice export duty" and "export-linked low-price selling" occur. The major objective of this paper is to analyze the following problems assuming the reserve stock is not sold : i) What will be the market equilibrium situation? ii) What are the effects of changes of the three policy variables (i. e., the rate of export duty, and both the proportion which exporters are required to sell to the government and the price at which these sales occur) on the equilibrium? iii) How and by how much do producers' surplus, domestic consumers' surplus and the revenue of the Thai government at equilibrium for the above mentioned case differ from those at equilibrium under the condition of free trade? Further, how and by how much is the sum of the above three changed by government intervention in the Thai rice export market? Finally, the paper considers the equilibrium situation when the government sells a certain amount of rice out of the reserve stock.