Tyler Cowen points to this news article by Lauren Sandler:

Stunningly, the postponement of marriage and parenting — the factors that shrink the birth rate — is the very best predictor of a person’s politics in the United States, over even income and education levels, a Belgian demographer named Ron Lesthaeghe [and coauthor Lisa Neidert] has discovered. Larger family size in America correlates to early marriage and childbirth, lower women’s employment, and opposition to gay rights — all social factors that lead voters to see red.

All the analysis in the linked paper is at the state and county level. That’s fine but this is not going to tell you what is a “predictor of a person’s politics.” Cowen labels his post “Sentences to ponder,” and what I want to ponder is that people are so quick to jump from aggregate to individual patterns.

And, yes, I know that aggregate patterns are related to individual patterns but they’re not the same. In particular, from the evidence we’ve seen (and which we presented in our book), social issues are important for voters at the high end of the income scale, not the low end.

David Brooks catches this—-in his op-ed from 2004 that Cowen links to, Brooks explicitly labels the conservative “natalists” as being high income (“when people get money, one of the first things they do is use it to try to protect their children from bad influences. . . . It costs a middle-class family upward of $200,000 to raise a child. . . .”). Brooks is getting it right that it is higher income voters who are central to the culture war.

In summary, I’m not trying to slam or “debunk” the Lesthaeghe and Neidert article. I just think it should be understood as an aggregate, not individual, pattern, and interpreted in light of what we already know.

[Cross-posted at The Monkey Cage]

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Andrew Gelman is a professor of statistics and political science and director of the Applied Statistics Center at Columbia University.