In the most-shared article in the NYT last weekend, psychologist Meg Jay warned couples against living together before marriage. Hanna Rosin rolls her eyes:

Jay trotted out the usual clichés about women looking at living together as a step toward marriage while men see it as a way of putting off commitment. And then to elevate her argument beyond anecdotal evidence, she cited the famous "cohabitation effect,” a sociological finding that couples who live together are more likely to get divorced. The idea is based on old research from the 1980s. Recently Wendy Manning [of Bowling Green] has analyzed couples married since 1996 and found that the cohabitation effect "has almost totally faded. We just can’t detect it anymore."

In the 1980s cohabitation was much less common, so it’s possible that people who did it were somewhat more experimental to begin with. But in the last 10 years, cohabitation has become the norm. Nearly 60 percent of women aged 25-39 have lived with a partner and the number among younger women is nearly 80 percent. So, knowing that the divorce rate is going down, and then doing the simple math, it can’t be true that all those couples are more likely to get divorced, can it?

Hanna insists that "the train wreck are the 15-20 percent of what sociologists call 'serial cohabitors.'"