The other day I criticized Brad Wilcox and Bob Lerman for claiming that increasing marriage would reduce inequality. In that post I passed up the chance to reinforce a lesson about misleading claims regarding selection and unobserved factors by members of the right-wing family social science community.
Passages like the following have become standard for Wilcox when he makes overblown claims regarding the benefits of marriage. Here is the latest:
Notwithstanding this report’s extensive data analysis, we do not claim that the associations we find among family structure while growing up, marriage as an adult, and economic outcomes are definitively causal. … Even after netting out the effects of many observed differences among individuals, both marriage and economic well-being may be the result of some third factor, such as unobserved differences in personality or character … Moreover, most of the evidence in this report is descriptive and does not derive from a causal model. For all these reasons, this report cannot definitively assert that adolescent family structure and adult marital status have a causal impact on individual and family economic well-being. … Nevertheless, the evidence is widespread and consistent enough to suggest strong, causal positive roles for being raised in an intact family and for current marriage on a range of important economic outcomes for the average American.
So this is the criteria for evaluating whether selection and omitted variables are a problem — whether the “evidence is widespread and consistent enough”? No. The volume of evidence is irrelevant; what matters is what it means. If people with various kinds of advantages and privileges are more likely to get and stay married, then research that fails to take that into account will always show married people doing better than people who aren’t married. The evidence will be “widespread and consistent,” and that does not mean it means marriage is the cause of their advantages.
I think that repeating this over and over, having been corrected on it many times, qualifies as demagoguery, or the practice of a demagogue, as the OED defines it:
…a political agitator who appeals to the passions and prejudices of the mob in order to obtain power or further his own interests; an unprincipled or factious popular orator.
It’s appealing to passions and prejudices, and taking advantage of the credulity of the friendly media — and abusing their status as professional researchers, in Wilcox’s case with academic tenure — in the service of their own ideological and material interests.
I made this argument in a previous post, which demonstrated widespread and consistent evidence for an assertion that is probably not true because of obvious selection bias: Cars improve child health. There is no end to the ways you can demonstrate this pattern (and I controlled for income, to show how far that gets you), but the ubiquity of the evidence does not correspond with the veracity of the claim that the relationship is causal.
Real research addendum
If, unlike Wilcox and Lerman, you want to consider this set of issues seriously, I must say I don’t mean to imply that there is no causal effect of marriage on anything. But real research that rigorously takes selection into account usually finds the remaining (probable) effects of marriage are small, if still theoretically important. With earnings, for example, a substantial part of men’s marriage effect is due to selection — that is, men who are either already earning more or who are headed for higher earnings are more likely to get married. For example, this recent study by Christopher Dougherty finds that men’s earnings start rising on average more than five years before marriage. You could attribute this to the cultural power of marriage if you think it shows men getting their act together and earning more because they want or plan to get married, but there’s no evidence for that over the interpretation that marriage is a windfall that follows from other advantages — such as physical or mental traits or health, or social advantages such as rich networks of job and relationship connections (none of which is measured directly in the kinds of data we have for these purposes). Alexandra Killewald and Margaret Gough report a similar pattern, although it’s not the focus of their paper. Killewald, in another good piece, does a lot of selection checking for the positive effect of married fatherhood on men’s earnings, before coming down on the side of a causal story. But her effect, although important, is not anywhere near large enough to lift poor people out of poverty or substantially reduce income inequality in the unlikely event that marriage increased among low-income parents. That’s a different discussion. As I argued the other day, even if marriage is good for married people, those who aren’t married are very unlikely to get the same benefit from marrying that we observe among the married population. They’re different people with different (mostly fewer) assets to capitalize on in marriage.