What causes increasing opportunity cost along a bowed out production possibilities frontier?

We see in Figure 2.4 "The Combined Production Possibilities Curve for Alpine Sports" that, beginning at point A and producing only skis, Alpine Sports experiences higher and higher opportunity costs as it produces more snowboards. The fact that the opportunity cost of additional snowboards increases as the firm produces more of them is a reflection of an important economic law. The law of increasing opportunity cost holds that as an economy moves along its production possibilities curve in the direction of producing more of a particular good, the opportunity cost of additional units of that good will increase.

We have seen the law of increasing opportunity cost at work traveling from point A toward point D on the production possibilities curve in Figure 2.4 "The Combined Production Possibilities Curve for Alpine Sports". The opportunity cost of each of the first 100 snowboards equals half a pair of skis; each of the next 100 snowboards has an opportunity cost of 1 pair of skis, and each of the last 100 snowboards has an opportunity cost of 2 pairs of skis. The law also applies as the firm shifts from snowboards to skis. Suppose it begins at point D, producing 300 snowboards per month and no skis. It can shift to ski production at a relatively low cost at first. The opportunity cost of the first 200 pairs of skis is just 100 snowboards at Plant 1, a movement from point D to point C, or 0.5 snowboards per pair of skis. We would say that Plant 1 has a comparative advantage in ski production. The next 100 pairs of skis would be produced at Plant 2, where snowboard production would fall by 100 snowboards per month. The opportunity cost of skis at Plant 2 is 1 snowboard per pair of skis. Plant 3 would be the last plant converted to ski production. There, 50 pairs of skis could be produced per month at a cost of 100 snowboards, or an opportunity cost of 2 snowboards per pair of skis.

The bowed-out shape of the production possibilities curve illustrates the law of increasing opportunity cost. Its downwards slope reflects scarcity.

Figure 2.5 "Production Possibilities for the Economy" illustrates a much smoother production possibilities curve. This production possibilities curve in Panel (a) includes 10 linear segments and is almost a smooth curve. As we include more and more production units, the curve will become smoother and smoother. In an actual economy, with a tremendous number of firms and workers, it is easy to see that the production possibilities curve will be smooth. We will generally draw production possibilities curves for the economy as smooth, bowed-out curves, like the one in Panel (b). This production possibilities curve shows an economy that produces only skis and snowboards. Notice the curve still has a bowed-out shape; it still has a negative slope. Notice also that this curve has no numbers. Economists often use models such as the production possibilities model with graphs that show the general shapes of curves but that do not include specific numbers.

Figure 2.5 Production Possibilities for the Economy

As we combine the production possibilities curves for more and more units, the curve becomes smoother. It retains its negative slope and bowed-out shape. In Panel (a) we have a combined production possibilities curve for Alpine Sports, assuming that it now has 10 plants producing skis and snowboards. Even though each of the plants has a linear curve, combining them according to comparative advantage, as we did with 3 plants in Figure 2.4 "The Combined Production Possibilities Curve for Alpine Sports", produces what appears to be a smooth, nonlinear curve, even though it is made up of linear segments. In drawing production possibilities curves for the economy, we shall generally assume they are smooth and "bowed out," as in Panel (b). This curve depicts an entire economy that produces only skis and snowboards.

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Have you been to a frontier lately? Whether you realize it or not, the economy has a frontier—it has an outer limit of economic production. In this episode of the Economic Lowdown Video Series, economic education specialist Scott Wolla explains how the production possibilities frontier (PPF) illustrates some very important economic concepts.

Segment 3 of The Production Possibilities Frontier uses the production possibilities frontier to demonstrate how, in the real world, opportunity cost increases as production increases. This is a difficult concept made simple using the PPF.

Watch other segments of this episode:

More episodes:

• The Economic Lowdown Podcast Series
• The Economic Lowdown Video Series

Transcript:

Below is the full transcript of this video presentation. It has not been edited for readability, and there may be slight differences between the text and the video.

Our final lesson focuses on the shape of the frontier line. Up to this point we've graphed the PPF as a straight line. However, a straight line doesn't best reflect how the real economy uses resources to produce goods. For this reason, the frontier is usually drawn as a curved line that is concave to the origin. This curved line illustrates our fifth and final lesson.

Lesson 5: The law of increasing opportunity cost: As you increase the production of one good, the opportunity cost to produce the additional good will increase.

First, remember that opportunity cost is the value of the next-best alternative when a decision is made; it's what is given up.

So let's compare straight and curved frontier lines to better understand what is more likely to happen when production changes.

Here's the straight frontier line again.

It shows that Econ Isle can produce a maximum of 12 gadgets and 6 widgets or any other combination along the line.

At this point, Econ Isle can produce 12 gadgets and 0 widgets. This point shows widget production increased by 2, and this by 2 more, and this by 2 more, indicating all widgets and no gadgets.

So along the straight line, each time Econ Isle increases widget production by 2, it loses the opportunity to produce 4 gadgets. This straight frontier line indicates a constant opportunity cost.

In reality, however, opportunity cost doesn't remain constant. As the law says, as you increase the production of one good, the opportunity cost to produce the additional good increases.

If Econ Isle transitions from widget production to gadget production, it must give up an increasing number of widgets to produce the same number of gadgets. In other words, the more gadgets Econ Isle decides to produce, the greater its opportunity cost in terms of widgets.

If Econ Isle's production moved in the opposite direction, from all gadgets to all widgets, the law would still hold: As you increase the production of one good, the opportunity cost to produce the additional good increases.

Why does this happen? Well, some resources are better suited for some tasks than others. For example, many Econ Isle workers are likely very productive gadget makers. In the transition to widget production, workers would likely need training and time to develop the skills required to be as productive at making widgets as making gadgets. As the economy transitions from gadgets to widgets, the gadget workers best suited to widget production would transition first, then the workers less suited, and finally the workers not at all well suited to widget production.

Here's where the curved frontier line comes in. It shows that opportunity cost varies along the frontier.

Let's increase widget production in increments of 2 again until only widgets and no gadgets are produced. But this time we'll consider opportunity cost that varies along the frontier.

This point remains the same. At this point, Econ Isle can produce 12 units of gadgets and 0 widgets.

Here's widget production increased by 2. At this point, Econ Isle can produce 10 gadgets and 2 widgets. It loses the opportunity to produce 2 gadgets. In other words, the opportunity cost of producing 2 widgets is 2 gadgets.

Here's widget production increased by another 2. At this point, if Econ Isle produces 6 gadgets, it can produce only 4 widgets, so it loses the opportunity to produce 4 gadgets. In other words, the opportunity cost of producing 2 widgets is now 4 gadgets.

Finally, increasing by another 2, Econ Isle can produce 0 gadgets and 6 widgets. It loses the opportunity to produce 6 gadgets. In other words, the opportunity cost of producing 2 widgets is now 6 gadgets.

Although the production possibilities frontier—the PPF—is a simple economic model, it's a great tool for illustrating some very important economic lessons: The frontier line illustrates scarcity—because it shows the limits of how much can be produced with the given resources. Any time you move from one point to another on the line, opportunity cost is revealed—that is, what you must give up to gain something else. Points within the frontier indicate resources that are underemployed. In turn, movement from a point of underemployment toward the frontier indicates economic expansion. When the frontier line itself moves, economic growth is under way. And finally, the curved line of the frontier illustrates the law of increasing opportunity cost meaning that an increase in the production of one good brings about increasing losses of the other good because resources are not suited for all tasks.

I hope you have enjoyed your journey to the frontier and learned some valuable lessons about economics along the way.

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