More than ever, young people are living in their parents' basements.

You've surely heard that one before. The Washington Post, the New York Times, the New Republic, Salon, and others have repeated it over and over in the last few years. More than 15.3 million twentysomethings—and half of young people under 25—live "in their parents’ home," according to official Census statistics.

There's just one problem with those official statistics. They're criminally misleading. When you read the full Census reports, you often come upon this crucial sentence:

It is important to note that the Current Population Survey counts students living in dormitories as living in their parents' home.

When you were adjusting to your freshman roommate, you were "living with your parents." When you snagged that sweet triple with your best friends in grad housing, you were "living with your parents." That one time you launched butt-rattling bottle rockets at the stroke of midnight off your fraternity roof? I hope you didn't make too much noise. After all, you were "living with your parents," and mine definitely went to bed around 11.

If you want to get histrionic about demographic household arrangements, at least be accurate. This observation, for example, is true: "In 1968, young people between 18 and 31 were almost twice as likely to be married than to live at home with their parents, according to the Census; now they're more likely to live with their parents than be married." Definitional issues aside, the share of young people living "at home" is at a half-century high. The question is: Why?