Retirement savings is probably behavioral economists' greatest success story. It is a prototypical behavioral-economics problem because saving for retirement is cognitively hard - figuring out how much to save - and requires self-control.

People worry that if they buy an annuity and then die before the policy starts to pay off, their heirs will lose out. I tell them, "What you should be more worried about is if you outlive your money, you will have to move in with your kids. Ask your kids which of these outcomes they are more worried about."

Most people start claiming benefits within a year of when they become eligible, although benefits increase substantially if they wait.

It would be much more consumer friendly for them to beep you when you swipe your card that says, uh-oh you're over your limit, are you sure you want to use that?

Why tie to gold? Why not 1982 Bordeaux?

Rip Van Winkle would be the ideal stock market investor: Rip could invest in the market before his nap and when he woke up 20 years later, he'd be happy. He would have been asleep through all the ups and downs in between. But few investors resemble Mr. Van Winkle. The more often an investor counts his money - or looks at the value of his mutual funds in the newspaper - the lower his risk tolerance.

There's a second component of a good savings plan, which is something that a colleague of mine called Schlomo Benartzi and I developed many years ago, that we call "save more tomorrow."