Topic 1.2 Notes – Opportunity Cost and the Production Possibilities Curve (PPC)

1. What the Production Possibilities Curve Is

The Production Possibilities Curve (PPC) shows all the possible combinations of two goods an economy can produce when it uses its resources fully and efficiently.

We assume:

• Only two goods
• Fixed resources (land, labor, capital, entrepreneurship)
• Fixed technology
• The economy is at full employment unless shown otherwise

Here’s what a standard PPC looks like:

Production Possibilities Curve (PPC)

What the Points Mean

• On the curve → Productive efficiency (all resources fully used)
• Inside the curve → Inefficiency (unemployment, recession, underused resources)
• Outside the curve → Unattainable with current resources/technology

The PPC exists because of scarcity. Resources are limited, so producing more of one good means giving up some of another.

2. Opportunity Cost and Tradeoffs on the PPC

Every movement along the PPC shows a tradeoff.

If you produce more of Good X, you must give up some Good Y. That loss is the opportunity cost, which means the value of the next best alternative given up.

Calculating Opportunity Cost

The formula you need to know:

$$\text{Opportunity Cost of Good X} = \frac{\Delta \text{Good Y}}{\Delta \text{Good X}}$$

Example from a table:

Moving from A to B:

• Gain = 10 cars
• Give up = 20 computers
• OC of 1 car = $20/10 = 2$ computers

Moving from B to C:

• Gain = 10 cars
• Give up = 30 computers
• OC of 1 car = $30/10 = 3$ computers

Opportunity cost is increasing here. That pattern matters.

Always label opportunity cost in terms of what is given up. Students lose points for flipping it.

You can also calculate opportunity cost using time:

$$\text{OC of X} = \frac{\text{Time to produce X}}{\text{Time to produce Y}}$$

3. Efficiency, Inefficiency, and Unattainable Points

Productive Efficiency

Any point on the curve. Maximum output using available resources.

Allocative Efficiency

The point on the PPC that reflects what society prefers most.

All allocatively efficient points are productively efficient. But not all productively efficient points are allocatively efficient.

Example: During World War II, the U.S. moved production toward military goods instead of consumer goods. That was a different allocative choice, even though production was still efficient.

Inefficiency

Points inside the curve.

• High unemployment during the Great Depression
• Recession during the 2008 financial crisis

An extreme interior point signals severe economic downturn.

Unattainable

Points outside the curve.

Only reachable if the PPC shifts outward.

4. The Shape of the PPC and Types of Opportunity Cost

Increasing Opportunity Cost (Most Realistic)

The PPC is bowed outward (convex).

Why? Resources are specialized. Workers and machines are not equally good at producing both goods. As you shift resources, you give up more and more.

That’s why most PPCs look curved.

Constant Opportunity Cost

The PPC is a straight line.

This happens when resources are perfectly adaptable between goods.

Decreasing Opportunity Cost

Bowed inward. Not realistic. Rarely tested.

5. Shifts of the PPC and Economic Growth

When the PPC shifts, the economy’s full employment level of output changes.

Outward Shift = Economic Growth

Causes:

• Increase in quantity of resources (immigration increases labor)
• Improvement in quality of labor (education, training)
• Technological advancement (Industrial Revolution, internet, AI)
• Investment in capital goods (factories, machines)

Capital vs. Consumer Goods

If an economy produces more capital goods today, it grows more in the future.

This is why rebuilding after WWII and infrastructure investment in countries like South Korea led to strong long-run growth.

Inward Shift = Economic Contraction

Causes:

• War destruction
• Natural disasters
• Loss of labor force
• Capital destruction

Technology That Affects Only One Good

The PPC shifts outward more on one axis.

Example: A breakthrough in computer chip production increases maximum computers but not cars.

Trade can also expand consumption possibilities beyond the PPC, but the curve itself reflects domestic production capacity.