I wonder how many of these factors are causation vs correlation. My guess is that, for example, that eloping doesn't ruin your marriage and having a big wedding doesn't improve it; it's just that people who elope are reflecting the reality that their attitude is "we're in this alone", and people who have a big wedding are reflecting their confidence and their sense that friends' and families' support is important.
As someone who dabbles in psychology research (mostly Big Five stuff), I had this same reaction: this is great correlation stuff, but I hardly expect it's casual. This is my grip with books like "The Seven Habits of Highly Effective People" -- picking up those habits won't make you necessarily effective.
