0455 · 1.4Production possibility curve (ppc) diagrams

Scarcity and reading PPC diagrams

0:00Imagine an economy producing food and clothing using its available workers, land and machinery. Producing more clothing may mean moving resources away from farming. Yet sometimes both outputs can rise without either being sacrificed. By the end of this video, you will understand how a production possibility curve explains these different situations. The starting point is scarcity, which means resources are limited compared with people’s wants. Production uses resources such as workers, machinery and natural materials.

0:27Choosing one use can mean giving up another. Opportunity cost is the next best alternative forgone when a choice is made. A production possibility curve shows the maximum combinations of two goods or services an economy can produce when all its resources are fully and efficiently used. The state of technology is taken as given. We will call this a P P C. It represents a production limit, rather than the combination people necessarily want.

0:51Each position on that boundary shows a different possible allocation of resources. Our diagram measures clothing along the horizontal axis and food along the vertical axis. Both outputs are measured per day, so we are comparing production over the same period. The clothing figures represent thousands of garments, while food is measured in tonnes. Always read the axis labels before interpreting a point. The food intercept shows a maximum of one hundred tonnes when no clothing is produced.

1:16At the other intercept, the economy makes eighty thousand garments but no food. Between those extremes, resources are shared across both activities. At point A, production is twenty thousand garments and ninety tonnes of food. Point B represents forty thousand garments and seventy tonnes of food. Further along the curve, at C, food drops to forty tonnes while clothing reaches sixty thousand garments. These combinations are alternatives, not outputs the economy produces simultaneously.

1:43The curve joins the maximum achievable combinations between the marked positions.

PPC shape and point positions

1:48To draw a P P C, begin with two clearly labelled axes showing the goods being produced. Then draw a downward-sloping curve bowed outwards from the origin. Its downward slope shows the trade-off when resources are fully and efficiently used. Increasing one output requires resources to leave the other activity. The bowed shape reflects differences between resources. Some workers and equipment are better suited to clothing production, while other resources are particularly useful for farming.

2:15The first resources moved are those best suited to clothing, so little food is lost. Later transfers remove highly productive farming resources, causing larger food losses. A point on the curve means resources are fully and efficiently used. Full use means no productive resources are left idle. With efficient use, the economy cannot produce more of one good without producing less of the other. However, this does not prove that the combination best meets society’s needs.

2:42Point U is inside the curve, at twenty thousand garments and forty tonnes of food. This output is attainable, but the economy is not reaching its production potential. Some resources may be unemployed, such as workers without jobs or idle machinery. Alternatively, resources may be used inefficiently through poor organisation or unsuitable methods. Moving from point U towards the boundary means making better use of existing resources. For example, employing idle workers could increase clothing production while food output remains unchanged.

3:10With enough unused capacity, both goods could increase together. The curve stays in place because the economy’s productive potential has not changed. Point V is outside the curve, at sixty thousand garments and ninety tonnes of food. This combination is unattainable with the economy’s current resources and technology. No reallocation of existing resources can reach it. Getting there requires the economy's productive capacity to increase. The distinction is between what an economy currently produces and what it could produce.

3:39An interior point describes output below its potential. The boundary shows its present limit, while an exterior point lies beyond that limit. A position outside today’s curve could become attainable after economic growth.

Calculating opportunity cost

3:51Consider a movement from point A to point B. Clothing output rises from twenty thousand to forty thousand garments per day, while food production falls from ninety to seventy tonnes. The economy has reallocated resources between activities, rather than increased its overall productive capacity. We calculate the extra clothing by subtracting twenty thousand from forty thousand garments. That gives twenty thousand additional garments per day. To identify the sacrifice, subtract seventy tonnes from ninety tonnes of food.

4:19The opportunity cost of this change is twenty tonnes of food per day. Notice that the opportunity cost is the food forgone, not the clothing gained. It is also not the seventy tonnes still being produced. We compare the starting combination with the finishing position to find the sacrifice. Always include the good and its units when stating your answer. Now consider moving from point B to point C. Clothing again increases by twenty thousand garments, from forty thousand to sixty thousand.

4:46This time, food falls from seventy to forty tonnes, giving a sacrifice of thirty tonnes per day. The same additional clothing therefore has a larger opportunity cost. This increasing sacrifice explains the outward-bowed shape. As clothing expands, resources increasingly valuable in farming must be transferred. Their removal causes progressively larger food losses. You do not need a complicated formula to understand this relationship; compare what is gained with what must be forgone.

Shifts in productive capacity

5:12An outward shift is different from a movement along the existing curve. It means the economy can now produce combinations that were previously unattainable. This represents economic growth in the sense of increased productive capacity. Both goods can potentially increase without the original trade-off forcing one to fall. More resources can expand this capacity, such as additional workers or newly available productive land. Improving the quality of resources also helps, for example by giving workers better skills.

5:41Investment adds or improves machinery and other capital equipment. Better technology can raise output from the same quantity of inputs. Each cause changes what the economy is capable of producing. Training may allow workers to complete tasks more effectively, while improved machinery can increase output per hour. An economy that produces more capital goods today, such as machinery, can expect its curve to shift further outwards in the future. The actual combination produced still depends on how resources are used and allocated.

6:09An outward shift does not guarantee that the economy immediately produces on its new boundary. Unemployment or inefficient organisation could leave actual output inside the expanded curve. Equally, moving from an interior point towards the existing boundary can increase production without shifting it. Keep higher actual output separate from greater productive capacity. A technological improvement may benefit only one industry. Suppose better machinery raises clothing productivity but leaves farming methods unchanged.

6:37The maximum clothing output increases, while the maximum food output stays the same. The curve therefore pivots outwards towards the clothing axis rather than shifting equally in both directions. Productive capacity can also fall, shifting the curve inwards. A natural disaster or war may destroy machinery, farmland and infrastructure. Resource depletion can reduce available natural inputs, while workers who move abroad take their skills with them. These changes reduce the maximum combinations the economy can produce.

7:06Environmental sustainability matters because some production decisions damage resources needed in the future. For example, degrading farmland may eventually reduce an economy’s capacity to produce food. Protecting soil can help preserve that potential. A P P C shows production possibilities, but it does not directly measure environmental quality or people’s wellbeing.

Exam technique and recap

7:25A common exam mistake is drawing an outward shift simply because previously unemployed workers find jobs. Existing unused resources becoming employed usually means movement towards the current boundary. Another mistake is treating every point on the curve as equally desirable. Productive efficiency does not tell us which combination society prefers. Multiple-choice questions may test whether a change represents reallocation, improved resource use or a shift in capacity. Structured questions can ask you to draw a diagram or explain a point’s position.

7:55For define, give the precise meaning of the term. A state question needs only a brief, direct answer with no explanation. Suppose a question asks you to explain why a point lies inside a production possibility curve. A suitable answer is that some resources are unemployed or used inefficiently. The economy therefore produces less than its maximum attainable output. Better use of existing resources could move production towards the boundary.

8:20For analyse, develop the relationship between cause and consequence. Consider the instruction to analyse how improved worker skills affect a production possibility curve. Training can raise labour productivity. Greater output becomes possible from existing resources, increasing productive capacity and shifting the curve outwards. For discuss, give an argument for, an argument against and a justified conclusion. Suppose the question concerns whether spending on education will increase productive capacity. Education can improve skills and productivity, allowing the curve to shift outwards.

8:51However, poorly designed training may bring little benefit, and useful skills can take years to develop. On balance, education is likely to shift the curve outwards in the long run, provided the skills taught match those that firms need. The P P C brings several ideas together in one diagram. Points on the boundary show full and efficient resource use, while interior positions indicate unused or inefficiently employed capacity. Exterior combinations are unattainable with current resources and technology.

9:19Moving along the curve reallocates resources and reveals opportunity cost. An outward shift represents increased productive capacity, while an inward shift shows that capacity has fallen. Improvements limited to one industry can expand only one intercept. Always ask whether a change affects resource allocation, the use of existing capacity or the production limit itself. That distinction lets you explain the diagram rather than simply memorise its shape.