Comparative Advantage & Trade — Quick Notes

Absolute Advantage

• Absolute advantage: ability to produce more of a good with the same resources.

• Example: A country or firm can produce more of a good than another with the same inputs.

• Importantly: having absolute advantage in all goods does not preclude gains from trade.

Comparative Advantage

• Comparative advantage: ability to produce a good at a lower opportunity cost than another producer.

• Determined by comparing opportunity costs using data from PPCs or tables.

• Key idea: trade based on lower relative (opportunity) costs, not on who can produce more overall.

Opportunity Costs and the PPC (Production Possibilities Curve)

• Compare costs by ratios of foregone goods when producing more of one good.

• Cost ratios (example from slides):

  • US: producing one unit of beef costs one unit of vegetables: $1V = 1B$

  • Mexico: producing one unit of beef costs two units of vegetables: $2V = 1B$

• Conclusion: US has comparative advantage in beef; Mexico has comparative advantage in vegetables.

Gains from Trade and Specialization

• Specialization according to comparative advantage expands consumption possibilities beyond the PPC.

• Terms of trade are the trading prices that make both sides better off.

• How to determine terms of trade: find a range that makes both sides better off.

  • If US is willing to trade beef for vegetables, and the base costs are $1B = 1V$ (US) and $1B = 2V$ (Mexico), then a mutually beneficial range is:

  • 1V < 1B < 2V

  • A concrete example within this range: $1B = 1.5V$

Process to Analyze Trade (Steps)

• Step 1: Calculate cost ratios (opportunity costs) for each good in each country.

• Step 2: Determine which country has the comparative advantage in each good.

• Step 3: Specialize in the lower-cost good.

• Step 4: Determine the terms of trade that make both sides better off.

• Step 5: Engage in trade and realize gains.

Classic US vs Mexico Example (Beef and Vegetables)

• Comparative advantages: US in beef; Mexico in vegetables.

• Specialization: US focuses on beef; Mexico focuses on vegetables.

• Terms of trade must lie between the two country’s opportunity costs: 1V < 1B < 2V

• Example terms of trade: $1B = 1.5V$ (mutually beneficial)

Specialization and Trade Summary

• Summary rule: Specialize in the good with the lower opportunity cost; trade to obtain the other good.

• Trade enables consumption beyond domestic production possibilities.

• Final relation: trade occurs at terms of trade that lie between the two nations’ opportunity costs.

Practice – Output Method (Problems)

• Data (example):

  • Newland: Cloth = 10 units, Food = 2 units

  • Beeland: Cloth = 10 units, Food = 1 unit

• (a) Opportunity cost calculations (Output method):

  • Cost of producing 1 unit of Cloth in Newland: $rac{2}{10} = 0.2 ext{ Food per Cloth}$

  • Cost of producing 1 unit of Food in Beeland: $rac{10}{1} = 10 ext{ Cloth per Food}$

• (b) Comparative advantages:

  • (i) Comparative advantage in Cloth: Beeland (lower cost per cloth: $0.1 ext{ Food per Cloth}$ vs. Newland’s $0.2 ext{ Food per Cloth}$)

  • (ii) Comparative advantage in Food: Newland (lower cost per food in terms of cloth)

• (c) Beeland productivity triples for each good:

  • (i) Which country has a comparative advantage in food now? Newland.

  • (ii) Explanation: Beeland’s costs rise for food relative to cloth after tripling, altering relative opportunity costs.

Practice – Input Method (Problems)

• Time-based approach (Input Method) converts time to inputs.

• Example approach: convert input times into output possibilities (or IOU method).

• Key idea: express one good in terms of the other using input times.

Input Method – IOU Method (Example)

• IOU stands for Input Other goes Under: time to produce one good can be converted into time forgone for the other.

• Example: If making a taco takes 10 minutes and a cake 20 minutes (per worker): 1T = 10/20 = 0.5C; 1C = 20/10 = 2T.

• This yields the same comparative conclusions as the output method when applied consistently.

Practice – Input Method (Questions)

• Example prompts:
  1) Who has the absolute advantage in app production?
  2) Who has the comparative advantage in app production?

Important Insight and Misperceptions

• A country with absolute advantage in all goods can still gain from trade due to comparative advantage.

• It is not possible for a country to have a comparative advantage in all goods.

• Self-sufficiency can lead to lower overall welfare; specialization and trade typically improve living standards.

Key Terms (Definitions)

• Absolute advantage: the ability to produce more of a good than another entity, given the same resources. For example, if Owen can embroider 10 pillows and Penny 15, Penny has absolute advantage in pillows.

• Comparative advantage: the ability to produce a good at a lower opportunity cost than another entity. For example, if producing a pillow costs Owen 2 scarves while Penny’s cost is 3 scarves, Owen has comparative advantage in pillows.

• Specialization: when an individual or country concentrates resources on a particular good or service.

• Trade: the exchange of goods, services, or resources between agents.

• Gains from trade: the increase in consumption possibilities from specializing according to comparative advantage and trading.

• Terms of trade: the price of one good in terms of another that two countries agree to trade at; it must be beneficial for both sides to realize gains from trade.

• International trade: the exchange of goods, services, or resources between countries.

• Gaps: Without trade, economies are limited by their PPC; with trade, they can reach beyond it through specialization and exchange.