One of the core principles of trade economics is that of “comparative advantage.” First described by David Ricardo, the theory says that countries are best off if they specialize in products that they can make relatively more efficiently – with lower opportunity cost – than other countries. If this happens, the theory goes, global welfare will increase. This concept is more difficult than it sounds, however – as Paul Krugman has pointed out quite eloquently – and benefits from illustration.

Basketball genius Michael Jordan stars in one example sometimes used in textbooks and classrooms: If Jordan mows his lawn faster than anyone else in the neighborhood, he has anabsolute advantage in lawn mowing. But that doesn’t mean that he should mow his neighbor John Smith’s lawn, because that would come at an opportunity cost: in the same two hours it would take Jordan to cut the grass, he could earn much more by playing basketball or making a commercial.

While it is difficult to measure comparative advantage in world trade, one indicator is something called “Revealed Comparative Advantage” (RCA). This is a measure of how a country’s exports compare to those of a bigger group, such as a region or the rest of the world. For example, if a country’s RCA in wheat is high (typically greater than one), that means wheat makes up a higher share of that country’s total exports than it does of the world’s exports. This suggests that that country is a more efficient wheat-producer than the average country.

But countries don’t always produce the products in which they have a revealed comparative advantage. Sometimes Michael Jordan mows the lawn. Let’s take a look at a couple of examples from this new data visualization tool.