Production possibility curve diagrams — common mistakes

When asked to illustrate a concept like unemployment or a recession on a PPC diagram, you must show it as a point inside the curve, not as an inward shift of the curve itself. An inward shift represents a reduction in the economy's potential output, whereas unemployment means the economy is simply not utilising its existing potential.

When OC rises along a bowed PPC, explain specialisation — resources are not equally suited to producing both goods.

No, not in the traditional sense. When an economy moves from an inefficient point (e.g., high unemployment) to a point on the curve, it can increase the output of both goods. This is sometimes called a 'free lunch' because output increases without sacrificing another good. The real opportunity cost was the potential output lost while the economy was operating inefficiently.

No, not with its current resources and technology. Points outside the curve are defined as unattainable. To reach such a point, the economy must first experience economic growth, which involves shifting the entire PPC outwards. A point outside the current PPC can be a future goal, but it is not a current possibility.

Not necessarily. While all points on the PPC are productively efficient (maximum output), they are not all allocatively efficient. Allocative efficiency is achieved at the single point on the PPC that represents the combination of goods and services most desired by society. The choice of which point to produce at depends on a society's priorities and values, for example, the choice between producing more capital goods for future growth versus more consumer goods for current satisfaction.