I think more likely the decline in "family household" formation is a result of the decline of marriage: See Population Reference Bureau (PRB) data.
Now, whether or not the decline of marriage is caused by economic factors is debatable. I think it probably partially is because unmarried couples who lost one income in the recession perhaps delay marriage while one of them moves in with a parent or roommate to share expenses, and/or the one-income earner is not confident in supporting two people, or both. There are also cultural trends that cause the marriage rate to bounce up and down over the decades, and these too then could be confounding the variables that go into the mix of what makes family household formation dip starting in 2008.
Decline in US marriages (Source: PRB)
Just my two cents...
As for the decline of violence, marriage is a causal variable in the decline (as marriage rates go up crime declines) because, as Pinker says, the number one predictor of violence is maleness, particularly young males, and one thing that marriage does in addition to lowering testosterone rates (which go down even more with children) is that it takes young men off the street and away from bars where they get into fights over status and women with other young males, all accentuated by the inhibition lowering effects of alcohol! For more on the topic please read The Better Angels of Our Nature: Why Violence Has Declined by Steven Pinker.
Monday, January 16, 2012
Shermer: decline in marriage likely cause of slow household formation
Dr. Michael Shermer is the Founding Publisher of Skeptic magazine, the Executive Director of the Skeptics Society, a monthly columnist for Scientific American, the host of the Skeptics Distinguished Science Lecture Series at Caltech, and Adjunct Professor at Claremont Graduate University.