Sendhil Mullainathan

Economists specialize in pointing out unpleasant trade-offs - a skill that is on full display in the health care debate. We want patients to receive the best care available. We also want consumers to pay less. And we don't want to bankrupt the government or private insurers. Something must give.

Faced with a time shortage, we squeeze tasks into the nooks and crannies of our calendar, leaving less and less time to switch between them. As a result, we become less and less productive exactly when we need to be most productive.

The problem with data is that it says a lot, but it also says nothing. 'Big data' is terrific, but it's usually thin. To understand why something is happening, we have to engage in both forensics and guess work.

There's a popular image of people who don't save for the future as lacking in self-control. But the reason saving is so hard has less to do with self-control and more to do with a scarcity of attention.

January is always a good month for behavioral economics: Few things illustrate self-control as vividly as New Year's resolutions. February is even better, though, because it lets us study why so many of those resolutions are broken.

Busy people all make the same mistake: they assume they are short on time, which of course, they are. But time is not their only scarce resource. They are also short on bandwidth. By bandwidth I mean basic cognitive resources - psychologists call them working memory and executive control - that we use in nearly every activity.