I overspoke myself on Twitter

Possibly not the only time.

A blog called Random Critical Analysis (RCA) has posted, “On Philip Cohen’s knee-jerk response to Chetty’s “causal mobility” data and its association with single-motherhood.” I now must admit that I overspoke myself on Twitter.

But I think the blog post I wrote holds up OK. I complained in the post that the now-famous Chetty et al. analysis of intergenerational mobility had mishandled race, leading to people like David Leonhardt (and rightward from there) to conclude that the big story of hampered social mobility is family structure. It’s part of the overall pattern of polite society embracing the issue of economic inequality but also using that as a foil to avoid the issue of race inequality.

Brad Wilcox has seized on the Chetty analysis, repeating ad nauseum the quote that single parenthood is the “single strongest correlate of upward mobility.” My beef was, and is, that the analysis that was based on — which used the rate of single parenthood at the labor market level to predict intergenerational mobility — did not control for the racial composition of the labor market. That’s an obvious problem when your map of mobility looks like this:

mobilitymap

When your analysis is ecological, that is, based only on aggregate characteristics, you have to be very cautious about drawing conclusions. It’s especially dicey in the Chetty case because the basic data, from tax, returns, includes family structure (because of parents’ marital status) but not race (which doesn’t go on your tax form). And that’s even more dicey because we know that at the individual level single parenthood is definitely not the “single strongest correlate of upward mobility.” I’ve been writing about this for years (follow the single-mother tag), but this figure from 2012 sums it up nicely (details in the old post):

You just have to keep that in perspective when you jump to an aggregate-level analysis. The difference between averages in Atlanta versus Salt Lake City — important as it is — is never going to be as big as the difference between a rich family and a poor family. Social parents’ class matters much more for determining children’s social class than does family structure.

Anyway, RCA is reworking my very simple analysis showing the effect of single motherhood rates was reduced by two-thirds when a single control for racial composition (percent Black) was added. That’s making the obvious point that, because single parenthood and percent Black in the local area are so strongly correlated, if you don’t take percent Black into account it looks like single parenthood has a huge, independent effect — which incorporates the effects of racism or other community factors associated with historical race composition. The new RCA post goes much further in the analysis, and concludes:

It ought to be pretty clear by now single-motherhood is capturing something quite powerful and that, contrary to Cohen’s strong assertions, it is not well explained by race.  If anything, single-motherhood mediates the black association much better than the reverse.

I’m not persuaded by the conclusion; you can evaluate it yourself. But the premise of the RCA post is actually not my blog post, but my tweets. As time went by I apparently became frustrated at the continued repetitions of the single mother thing by people who were ignoring my very clever post, and with the carelessness that distance allows I overstated my own claim, so I tweeted this,

The table and the highlighting are mine. What I should have paid attention to was my own next sentence after the underlined part: “That’s not an analysis, it’s just an argument for keeping percent Black in the more complex models.” I didn’t do a serious analysis — I just did enough to prove the point that racial composition should be in the model. Without that, you shouldn’t run around saying single parenthood is the most important factor. (RCA also believes I shouldn’t have said in the post that “Percent Black statistically explains the relationship between single motherhood and intergenerational immobility.”  I think “explains” is defensible, in that the effect is no longer statistically distinguishable from zero at the conventional level, but it’s clearly not the same as proving there is no effect, so I’ll take the criticism, too.)

I actually first did the little analysis in an earlier post, debunking a univariate analysis by Scott Winship and Donald Schneider. In that case I concluded: “This [my analysis] is not a rigorous examination of the cause of intergenerational immobility. It is just debunking one bivariate story that is too easily picked up by the forces of bad.” That seems about right.

Anyway, in conclusion, it was incorrect based on what I did for me to tweet, “the single mother effect in Chetty is all in the % Black effect.” I should just say single parenthood hasn’t been proven to matter as much as its partisans say it has. Even if it’s less effective in a tweet. This is a common frustration, that it takes more work to debunk something than to bunk it in the first place. But that’s not a good excuse.

Finally, I’m grateful that what I write matters enough that someone would go to the trouble of testing my claims to hold me accountable.

3 Comments

Filed under Me @ work

3 responses to “I overspoke myself on Twitter

  1. Swoosh

    But this shows the bigger problem: You are reflexively defending monomoms. You are a feminist who prefers to whiteknight instead of doing solid science. You are a nice example of how modern science has been infested by liberals and feminists.

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    • On the contrary, “reflexive” and non-analytical defensiveness is when you attack someone based on prejudicial feelings rather than logic or evidence…You know, like what you just did to Philip Cohen after he explained his conclusion, which is clearly based on logic and evidence.

      Like

  2. Renee

    Chetty was the keynote at FCSM this year and after being very concerned about the presentation I came to see if you had anything to say about his work and was happy to see this.

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