University of Virginia sociologist Bradford Wilcox has published a study of the effects of cohabitation, couples living together without marriage. He especially looked at the impact on children when their parents are not married. He quantified his study by examining what percentage of children over time are still living with their parents.
Now one could deduce using common sense that couples who are not married are going to have less stable families, with children being adversely affected. This study, though, gives an abundance of empirical data. Not only that, it looks at cohabitation globally, finding consistent patterns across nationalities and cultures. And it explodes at least three common myths that people had assumed about cohabitation.
The complete study is here. Read an interview with Prof. Wilcox on his findings after the jump.