Production possibility curve (PPC) diagrams

Economics is built on a simple but powerful idea called the basic economic problem: our wants are unlimited, but the resources available to satisfy them are limited. 'Wants' are the goods and services we desire, from a new phone to better healthcare. 'Resources', also known as factors of production (land, labour, capital, enterprise), are the inputs used to make these goods and services. Because resources are finite, or 'scarce', we cannot have everything we want. This forces everyone—individuals, firms, and governments—to make choices. We must decide what to produce, how to produce it, and for whom to produce it, because we cannot produce everything for everyone.

Every time a choice is made, an alternative is given up. The value of this 'next best alternative' that is sacrificed is called the opportunity cost. It is the true economic cost of a decision. For example, if a business uses its factory to produce 1,000 chairs, it cannot use the same factory, workers, and materials to produce 200 tables. The opportunity cost of producing the 1,000 chairs is the 200 tables that were foregone. Opportunity cost is not just about money; it is about the real goods and services that could have been produced or enjoyed instead.

A Production Possibility Curve (PPC) is a diagram that shows the maximum combinations of two goods that an economy can produce over a period of time, given that all its resources are fully and efficiently employed. The curve itself represents the boundary, or 'frontier', of what is possible.

• Points ON the curve (e.g., A, B): These points are productively efficient. The economy is using all its resources to the fullest extent. To produce more of one good, it must produce less of the other.
• Points INSIDE the curve (e.g., X): These points are inefficient but attainable. The economy is producing less than its potential, which could be due to unemployed resources like workers without jobs or idle factories.
• Points OUTSIDE the curve (e.g., Y): These points are currently unattainable. The economy does not have enough resources or a high enough level of technology to produce this combination of goods.

The PPC model can show both reallocation of resources and changes in an economy's total productive capacity.

1. Movement Along the PPC: This occurs when an economy changes its production choice, for example, producing more capital goods and fewer consumer goods. Moving from one point to another *along the curve* illustrates opportunity cost. To gain more of one good, some of the other good must be given up. The curve is typically 'bowed outwards' (concave to the origin) because of increasing opportunity cost. This means as you produce more and more of one good, you have to give up increasingly larger amounts of the other, as resources are not perfectly adaptable for producing both goods.

2. Shift of the PPC: The entire curve can shift. An outward shift represents economic growth. The economy's productive capacity has increased, making previously unattainable points now possible. This is caused by an increase in the quantity or quality of resources (e.g., discovery of new oil reserves, increased workforce, investment in new machinery) or an improvement in technology. An inward shift represents a fall in productive capacity, perhaps due to a war, natural disaster, or mass emigration.