Trade Theory – The Classical World of David Ricardo and Comparative Advantages
Concept:
Trade can make everyone better off. Imports are the real fruit of trade because the end goal of economic activities is consumption. Export represent resources we don’t consume at home.
貿易會帶給大家好處，事實上，出口未必對國家不好，因為經濟活動的最終目標就是消費，出口貿易則代表出口我們多餘、不需要的資源。
3.1 Assumption of the Basic Ricardian Model 李嘉圖模型的基本假設
1.Each country has a fixed endowment of resources, and all units of each particular resource are identical.
每個國家有固定的要素稟賦，每個單位的資源是可計算的。
(要素稟賦是指一國擁有各種生產要素，包括勞動力、資本、土地、技術、管理等的豐歉)
2.The factor of production are completely mobile between alternative uses within a country which implies that the price of factor of production also are the same among these alternative uses.
生產要素在國內不同的使用上自由移動，也就是生產要素在不同使用上，價錢會一樣。
3.The factor of production are completely immobile externally, which means factor price may differ from different country.
生產要素在不同國家不是自由移動，有不一樣的價格。
4.Labor theory of value is employed.
勞動價值說被採用- 產品的價值由勞動來衡量，也就是勞動時數。
5.Level of technology is fixed. 技術程度不變
6.Unit costs of production are constant.
生產的單位成本保持不變，重要！，任何產品的供給線是水平。造成完全專業化的重要因素。
7.There is full employment
國內充分就業。
8.Perfect competition, p=mc.
市場是完全競爭市場。
9.There’s no government-imposed obstacle to economic activities.
沒有政府限制經濟活動。
10.Internal and external transportation cost = 0.
內部與外部的運輸成本為零。
11.The analysis is confined to a two-country, two-commodity world.
用兩個國家的世界來簡化分析。
Comparative Advantage 比較利益
A country has comparative advantage on something when it has lower opportunity cost to produce on the good.
擁有比較利益代表生產某一項產品有較低的機會成本
Opportunity Cost機會成本
Whatever must be given up to get some item.
為了取得某項東西所需放棄的東西
Terms of Trade 貿易比率
一個國家每出口一個單位商品可以獲得多少單位的進口商品，也就是這個國家的出口商品相對於進口商品的相對價格。
Resource Constraints 資源限制
To illustrate gain from trade, you can first establish the amount of constraining resources to each country.
Complete Specialization 完全專業化
Complete specialization means that all the resources are devoted to the production of one good, which make countries experience greater gain.
3.2 Production-Possibilities Frontiers – Ricardian Model
The PPF shows the combination of two goods that a country can produce at a give point in time given its resource base, level of technology, full utilization of resource, and economically efficient production.
Under the assumption of constant-cost, the slope of the straight line represents the opportunity cost of economy-wide production.
