2/3/2023

Basics of Two-Country Trade: The Standard

Trade Model

Trade Between Two Countries

Japan Europe World Trade
Price D S D S D S J E
10 0 11 0 9 0 20 11 9
9 0 10 2 8 2 18 10 6
8 0 9 4 7 4 16 9 3
Europe
in
autarky
7 0 8 6 6 6 14 8 0
6 0 7 8 5 8 12 7 -3
Free
Trade 5 0 6 10 4 10 10 6 -6
4 1 5 12 3 13 8 4 -9
3 2 4 14 2 16 6 2 -12
Japan in
autarky 2 3 3 16 1 19 4 0 -15
1 4 2 18 0 22 2 -2 -18
0 5 1 20 0 25 1 -4 -20

Trade Between Two Countries

• Autarky means no international trade
• When two countries begin trading…
– The price of any traded good
• falls where it is expensive in autarky, and
• rises where it is cheap in autarky
– Eventually, the price becomes the same in both countries
– This global free trade price lies somewhere between the two autarky
prices

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Trade Between Two Countries

• When two countries begin trading, for any traded good …
– it is exported from where it is cheap in autarky to where it is
expensive in autarky, and
– it is imported to where it is expensive in autarky from where it is
cheap in autarky
– global quantity demanded = global quantity supplied
– exports = imports (in quantity and market value)

Trade Between Two Countries

• Balanced Trade Assumption: A country must pay for its
imports of some good (Good X) by exporting an amount of
equal market value of some other good (Good Y)
• In other words, if you import one good you must export
another good, and your exports and your imports must be
equal in market value

Trade Between Two Countries

• The previous slides imply that when a country begins trading …
– the price of its imported good falls, and
– the price of its exported good rises

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Prices: nominal and relative

• So far, I have been not been fully clear about how prices
are measured
• When the price of a good is measured in currency units, it
is called a nominal price
– Example: the nominal price of ice cream is $4.00 per quart
– Example: the nominal price of coffee is $1.00 per cup

Prices: nominal and relative

• When the price of one good is measured in units of another
good, it is called a relative price
– Example: suppose the nominal price of ice cream is $4.00 per quart
and the nominal price of coffee is $1.00 per cup.
– Then the relative price of ice cream is 4 cups of coffee per quart.
– And the relative price of coffee is ¼ quarts of ice cream per cup
• In my lectures on international trade, when I say “price” I
mean “relative price”

Graphical analysis of two-country trade

• Now, let us review our numerical analysis using graphs!
– Economists love graphs!

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This is how the worldwide free trade Europe has the higher autarky price. Europe becomes the
price is determined. Note that the free importing country. Prices fall. Production falls.
trade price ( ) must lie between the two
countries’ autarky prices ( ). Japan has the lower autarky price. Japan becomes the
exporting country. Prices rise. Production rises.

Note that Japan’s exports ↔ equal Europe’s imports ↔.

Price

Europe + Japan = World Quantity

Japan: The Exporting Country

Price
of Steel

Price Domestic
after supply
trade World
price
Price
before
trade

Domestic
Exports demand
0
Domestic Domestic Quantity
quantity quantity of Steel
demanded supplied

Europe: The Importing Country

Price
of Steel

Domestic
supply
Price
before
trade

Price World
after price
trade
Domestic
Imports
demand
0 Domestic Domestic Quantity
quantity quantity of Steel
supplied demanded

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Effect of Trade on Prices

• We have seen that when autarky ends and free trade begins in
a country
– the price of its imported good falls, and
– the price of its exported good rises

• How does this affect production and consumption?

Effect of Trade on Production

• When autarky ends and free trade begins,
– the production of the exported good increases, and
– the production of the imported good decreases
• See the section “Production Possibilities and Relative Supply” and Figure 5-2 of the course’s textbook.

• As the availability of productive resources is always finite, if a

country produces more of something, it must produce less of
something else

Effect of Trade on Production

• When autarky ends and free trade begins,
– the production of the exported good increases, and
– the production of the imported good decreases
• Remember that trade raises the price of the exported good. This gives
producers of the exported good an incentive to raise production.
• Similarly, trade makes the imported good cheaper. This reduces the incentive
for domestic producers of the imported good to produce it.

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Effect of Trade on Consumption

• Unfortunately, we can’t be sure of the effects of free trade on
consumption
• All we can be sure of is that the consumption of either the
imported good or the exported good will surely increase

Effect of Trade on Consumption

• The effect of an increase in the price of beef (relative to steel)
on the consumption of beef works through two channels:
– Substitution effect: buy less of whatever has become more expensive
and more of whatever has become less expensive
– Income effect: trade has made you richer. So, act the way people act
when they get richer: buy more of normal goods and less of inferior
goods

Effect of Trade on Consumption

• Normal goods are goods that people buy more (less) of when
they get richer (poorer)
• Inferior goods are goods that people buy less (more) of when
they get richer (poorer)

• Q: Can you think of examples of normal and inferior goods?

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Effect of Trade on Consumption

• Suppose free trade leads to an increase in the price of beef
(relative to steel)
– Substitution effect: buy less beef and more steel
– Income effect:
• Trade has made you richer. So, act like you are richer!
• Buy more of whichever good is normal
• Buy less of whichever good is inferior
• So, the overall effect on beef and steel consumption is
uncertain

Effect of Trade on Consumption

• Suppose free trade leads to a decrease in the price of beef
(relative to steel)
– Substitution effect: buy more beef and less steel
– Income effect:
• Trade has made you richer. So, act like you are richer!
• Buy more of whichever good is normal
• Buy less of whichever good is inferior
• So, the overall effect on beef and steel consumption is again
uncertain

If the autarky equilibrium

price is the same for both
countries, no trade will occur
even when trade is allowed.
That is, similarity = no trade.

Price

Europe + Japan = World Quantity

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Similarity = No Trade
• If the pre-trade (or autarky) relative prices (of one good in
terms of another) are the same for the two countries, no trade
will occur.
– On relative prices, see the section “Relative Prices and Supply” of the course’s textbook.

As we saw before, if the autarky

equilibrium price is not the same for
both countries, trade will occur
when trade is allowed. That is,
dissimilarity = trade.

Price

Europe + Japan = World Quantity

Dissimilarity = Trade
• Trade will occur if the pre-trade (or autarky) relative price of
one good in terms of the other is not the same for the two
countries.
• The free trade relative price will be neither higher than the two autarky
prices, nor lower.
• Therefore, when the autarky relative prices are unequal, the free trade
relative price must be different from the autarky relative price for at
least one of the two countries.

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Reasons For Dissimilarity

• Three theories that explain why autarky prices may be high in
some countries and low in others:
– Ricardian Theory
– Specific Factors Theory
– Heckscher-Ohlin Theory

Opportunity Cost
• The opportunity cost of good X is the amount of good Y that
will have to be sacrificed when an additional unit of X is
produced
• Between two trading countries, one country is said to have a
comparative advantage in the production of a good if, in
autarky, the opportunity cost of the good is smaller in that
country

Opportunity Cost = Autarky Price

• In a perfectly competitive economy, the opportunity cost of
good X equals the autarky relative price of good X.
• Therefore, between two trading countries, one country is said
to have a comparative advantage in the production of a good
if the autarky relative price of the good is smaller in that
country

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Trade Follows Comparative Advantage

• We have seen that
– the country with the cheaper autarky price of a good becomes the
exporter of that good, and
– the country with the higher autarky price of a good becomes the
importer of that good
• Therefore, we can say that whichever country has a
comparative advantage in the production of a good becomes
the exporter of that good

Trade Reflects Comparative Advantage

• When autarky ends and free trade begins, each country
– increases its production of the good in which it has a comparative
advantage and
– exports that good.
• In other words, free trade follows the principle of comparative
advantage.

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