Though some generations may believe that living together before marriage is necessary for success while others think it's a recipe for disaster, a study released Tuesday claims cohabitation has very little affect on the long-term success of a marriage. The National Center for Health Statistics report, based on a sample of nearly 13,000 men and women, found little difference between couples who lived together first or didn't in first marriages that lasted at least 10 years. "On the basis of these numbers, there is not a negative effect of cohabitation on marriages, plain and simple," said one University of Michigan sociologist. Though it was assumed throughout the '70s, '80s, and '90s that cohabitation led to a high divorce rate, the study questions that theory. The new report shows that couples that live together before getting engaged or making a clear decision to get married are at a greater risk of divorce.