Comparative Advantage and Gains from Trade · 比较优势与贸易收益
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| trade/treɪd/ | 贸易 | mào yì |
| specialise/ˈspeʃəlaɪz/ | 专业化 | zhuān yè huà |
| comparative advantage/kəmˈpærətɪv ədˈvæntɪdʒ/ | 比较优势 | bǐ jiào yōu shì |
| absolute advantage/ˈæbsəluːt ədˈvæntɪdʒ/ | 绝对优势 | jué duì yōu shì |
| opportunity cost/ɒpəˈtjuːnɪti kɒst/ | 机会成本 | jī huì chéng běn |
| terms of trade/tɜːmz ɒv treɪd/ | 贸易条件 | mào yì tiáo jiàn |
Why trade if you're better at everything?
- Suppose your country can make more of every good than your neighbour.
- It sounds like you should just make everything yourself.
- Yet both countries end up richer if they each specialise and then trade.
- The reason is one of the most surprising ideas in all of economics: comparative advantage 比较优势.
已经样样都强,为什么还要贸易?
- 假设你的国家生产每一种商品都比邻国更多。
- 听起来,你应该什么都自己生产。
- 可是,如果两国各自专业化再进行贸易,双方都会更富有。
- 原因是全部经济学里最出人意料的观点之一:比较优势(comparative advantage)。
Absolute vs comparative advantage
- Absolute advantage 绝对优势 means making more of a good with the same resources.
- Comparative advantage 比较优势 means having the lower opportunity cost 机会成本 of making it.
- These are not the same: one producer can hold the absolute advantage in everything, yet the comparative advantage in only some things.
- For trade, the rule that matters is comparative, not absolute.
绝对优势与比较优势
- 绝对优势(absolute advantage):用同样的资源生产更多某种商品。
- 比较优势(comparative advantage):生产它的机会成本(opportunity cost)更低。
- 两者并不相同:一个生产者可以在所有商品上都有绝对优势,却只在部分商品上有比较优势。
- 对贸易来说,起作用的是比较优势,而不是绝对优势。
Absolute or comparative? · 绝对优势还是比较优势?
Absolute advantage is about making more; comparative advantage is about the lower opportunity cost. Only comparative advantage decides who should specialise. · 绝对优势看谁产量更多;比较优势看谁机会成本更低。只有比较优势决定谁该专业化。
A country has an absolute advantage in a good when it can: · 当一个国家在某商品上有绝对优势时,它能:
Absolute advantage is about raw output; comparative advantage is about opportunity cost. · 绝对优势看产量本身;比较优势看机会成本。
Work out who should make what
- Worked example. In one day: Country X can make 10 phones or 20 shirts; Country Y can make 4 phones or 4 shirts.
- X's opportunity cost of 1 phone is $20/10 = 2$ shirts; Y's is $4/4 = 1$ shirt.
- Y gives up fewer shirts per phone, so Y should make the phones.
- Checking shirts: X gives up $10/20 = 0.5$ phones each, Y gives up $1$ — so X should make the shirts.
算一算谁该生产什么
- 例题。 一天内:X 国能造 10 部手机或 20 件衬衫;Y 国能造 4 部手机或 4 件衬衫。
- X 造 1 部手机的机会成本是 $20/10 = 2$ 件衬衫;Y 的是 $4/4 = 1$ 件衬衫。
- Y 每部手机放弃的衬衫更少,所以 Y 应该造手机。
- 再看衬衫:X 每件放弃 $10/20 = 0.5$ 部手机,Y 放弃 $1$ 部——所以 X 应该造衬衫。
X: 10 phones or 20 shirts. Y: 4 phones or 4 shirts. Who has the comparative advantage in phones? · X:10 部手机或 20 件衬衫。Y:4 部手机或 4 件衬衫。谁在手机上有比较优势?
Y gives up 1 shirt per phone vs X's 2 shirts — Y has the lower opportunity cost. · Y 每部手机放弃 1 件衬衫,X 放弃 2 件——Y 的机会成本更低。
Country X can make 10 phones OR 20 shirts in a day. What is the opportunity cost of ONE phone, in shirts? · X 国一天能造 10 部手机或 20 件衬衫。一部手机的机会成本(以衬衫计)是多少?
Giving up 20 shirts frees enough to make 10 phones, so each phone costs $20/10 = 2$ shirts. · 放弃 20 件衬衫可换来 10 部手机,所以每部手机的成本是 $20/10 = 2$ 件衬衫。
Specialise, then trade
- Each producer specialises 专业化 in the good where its opportunity cost is lower.
- They then trade 贸易 for the rest, and both can consume beyond their own PPC.
- The terms of trade 贸易条件 (the swap rate) must sit between the two opportunity costs for both sides to gain.
- Remember: X was absolutely better at both goods, yet trade still made both better off.
先专业化,再贸易
- 每个生产者在机会成本更低的那种商品上专业化(specialise)。
- 然后用它贸易(trade)换取其余的东西,双方都能消费到超出各自 PPC 的组合。
- 贸易条件(terms of trade,即交换比率)必须落在两者机会成本之间,双方才都能获益。
- 记住:X 在两种商品上都绝对更强,可贸易仍然让双方都变得更好。
If one country is better at making every good, trade cannot benefit both sides. · 如果一个国家生产每种商品都更强,那么贸易就不能让双方都受益。
As long as opportunity costs differ, both gain from specialising and trading — even then. · 只要机会成本不同,双方就能从专业化和贸易中获益——即使在这种情况下也一样。
A producer should ______ in the good where it has a comparative advantage. · 一个生产者应在它有比较优势的商品上______。
Specialise where your opportunity cost is lowest, then trade for the rest. · 在机会成本最低的地方专业化,再贸易换取其余。
Select all · 所有 true statements about gains from trade. · 选出关于贸易收益的所有正确说法。
Both sides gain when they specialise by comparative advantage and trade at terms between their opportunity costs. · 当双方按比较优势专业化、并以介于机会成本之间的条件贸易时,双方都获益。
Comparative advantage is the lower opportunity cost — not making more (that is absolute advantage). Each producer should specialise where its opportunity cost is lower and trade for the rest. This works even if one producer is better at everything, and lets both consume beyond their own PPC.
比较优势是更低的机会成本——不是产量更多(那是绝对优势)。每个生产者应在机会成本更低的地方专业化,再贸易换取其余。即使一方样样都更强,这也成立,并让双方都能消费到超出各自 PPC 的水平。