Bill Gates: My Plan to Fix The World's Biggest Problems

We can learn a lot about improving the 21st-century world from an icon of the industrial era: the steam engine.

Harnessing steam power required many innovations, as William Rosen chronicles in the book "The Most Powerful Idea in the World." Among the most important were a new way to measure the energy output of engines and a micrometer dubbed the "Lord Chancellor" that could gauge tiny distances.

Such measuring tools, Mr. Rosen writes, allowed inventors to see if their incremental design changes led to the improvements—such as higher power and less coal consumption—needed to build better engines. There's a larger lesson here: Without feedback from precise measurement, Mr. Rosen writes, invention is "doomed to be rare and erratic." With it, invention becomes "commonplace."

In the past year, I have been struck by how important measurement is to improving the human condition. You can achieve incredible progress if you set a clear goal and find a measure that will drive progress toward that goal—in a feedback loop similar to the one Mr. Rosen describes.

This may seem basic, but it is amazing how often it is not done and how hard it is to get right. Historically, foreign aid has been measured in terms of the total amount of money invested—and during the Cold War, by whether a country stayed on our side—but not by how well it performed in actually helping people. Closer to home, despite innovation in measuring teacher performance world-wide, more than 90% of educators in the U.S. still get zero feedback on how to improve.