I’ve often blogged about the dangers of selection bias (see here and here). So in writing a book about education, I have to wonder: To what extent is my personal experience atypical?

My main answer: My personal experience exaggerates the practicality of education. After all, a big part of my job is teaching students the very material that other professors once taught me. Thus, it’s unusually easy for educators like me to connect classes we once took with tasks we now perform.

The test that really counts, however, is the extent to which the average student uses what he learned. Whenever I get a chance, I ask. It turns out that – leaving aside students who become professors themselves – classroom and workplace are practically disconnected. In fact, even people with degrees that I intuitively think of as “vocational” – like engineering and law – admit that the job they do has almost no connection to the classes they took.

Why then do employers pay my students more because I gave them A’s in labor economics and industrial organization? The answer my book will flesh out in gory detail: signaling. Employers pay big bucks to people who excel in impractical subjects because such people tend to be smart, conscientious, and obedient to authority – in short, to be good workers. It’s not what you learned – it’s what your learning shows about you.