Some people are better than others. "The others" just suck.
Hear, hear. This type of stuff is basically just a statistical trick. One merely needs to take married couples who have never lived together, a relatively small sample that is already predisposed to commitment, and compare them to every other couple thats ever lived together, for any reason. That's a huuuge sample that includes sub-groups such as, for instance, chronic drug users, untreated schizophrenics, lifelong economic refugees and your standard "find-a-guy-that'll-hit-me" women, all of whom subsequently skew the results of the whole Co-habitation group toward being more dysfunctional than the Married group.
Only a few seconds of thought is required to realize that the over-representation of these sub-groups in the co-habitating group has nothing to do with their choice not to marry, since, of course, getting married would do nothing to change their particular dysfunction. But their dysfunction does serve to reduce their tendency to want to marry, thereby dragging the success rate of any group they're included in down.
Its actually a pretty slick statistical manipulation.
Since you like "statistical tricks," here's another one for you. Couples who practice natural family planning, rather than using artificially induced sterility, enjoy a divorce rate of less than 5%. (Marital duration and natural family planning)
So basically, this "statistical trick" proves that couples who do not live together before marriage, and who joyfully welcome children into life, walmost never divorce.
This "statistical trick" used to be called common sense.