If you're trading individual securities, you're almost certainly making a mistake. Because most professional managers can't outperform their benchmarks, and there's little reason to think that individuals can.

When an economist says the evidence is "mixed," he or she means that theory says one thing and data says the opposite.

In the 1940s, economics started getting highly mathematical. It was basically because economists weren't smart enough to write down models of real behavior that they started writing down models of highly rational behavior - and they kind of forgot about humans.

Academia does not provide many opportunities for immediate gratification. You work for two years on a project, it takes two more years to get it published, and then you start hoping someone might read it.

In the world of traditional economics, it shouldn't matter whether you use an opt-in or opt-out system. So long as the costs of registering as a donor or a nondonor are low, the results should be similar. But many findings of behavioral economics show that tiny disparities in such rules can make a big difference.

My thesis topic was 'The value of a human life.' I asked people a question: 'Suppose you had some risk, a one in a thousand risk of dying - how much would you pay to eliminate it?'