Production Possibility Frontier

Scarcity, tradeoffs, and opportunity cost on one curve, what an economy can produce and what growth looks like.

Current equations

PPF: (X/80)² + (Y/80)² = 1

Everything an economy could produce with what it has. Points on the frontier are efficient; inside is waste; outside is impossible, for now. The curve bows outward because resources aren't equally suited to both goods: each extra unit of X costs more and more Y. That slope is opportunity cost, the most important idea in economics.

Shift the curves

Capacity for Good X (technology, resources)0

Better technology for X rotates the frontier outward along the X-axis only.

Capacity for Good Y (technology, resources)0

Better technology for Y rotates the frontier outward along the Y-axis only.

Overall growth (labor force, capital stock)0

Economy-wide growth shifts the whole frontier outward: more of both goods is possible.

The Production Possibility Frontier model, in writing

Definition

The production possibility frontier shows every combination of two goods an economy can produce when all resources are fully and efficiently employed.

Opportunity cost of good X = units of Y given up per extra unit of X (the slope)

The intuition

Points inside the curve waste resources, points on it are efficient, points beyond it are unattainable today. The bowed-out shape captures increasing opportunity cost: resources are specialized, so the more of one good you make, the less suited are the extra resources you pull in. Growth or technology shifts the whole frontier outward.

Exam tip

Distinguish a MOVEMENT along the PPF (choosing a different mix) from a SHIFT of the PPF (more resources or better technology). Unemployment is a point inside the curve, not an inward shift.

Related models in Micro Foundations

Absolute vs. Comparative Advantage →Supply & Demand →Price Elasticity of Demand & Supply →Consumer & Producer Surplus →