Posted by: Chris | September 25, 2010

Math and the Single Mom

Ta-Nehisi Coates attempts to demonstrate the marginal relevance of the widely cited stat that 70% of African-American births are out of wedlock, which is used often to buttress claims of a general familial breakdown in the United States and the consequences of the abandonment of the marriage ideal (see, for example, Ross Douthat’s post on gay marriage).  Coates argues that this statistic is misleading because the birth rate for unmarried black women has receded over the past 40 years, citing these reports from the CDC:  

The data to support this can be found here and here. In other words, no one disputes that 70 percent of black babies are born out of wedlock–or maybe they do, I never have. What we dispute are the reasons why. One notion that’s gained quite a bit of currency is that over the last 40 years, black mothers have, for whatever reason, decided that they’d much rather be single mothers. But the facts don’t back this up. As the data shows unmarried black women are having less, not more, kids then they were having 40 years ago.  

He argues that the out-of-wedlock birth rates have remained stable, despite this perceived decline in unmarried mothers (as a percentage of the whole unmarried population) because the birth rate for married African-American women has dropped even more:  

To summarize–there is no data to show that the black “illegitimacy” figure of 70 percent has been caused by unmarried black women having more kids than they did in the past. In fact, the trend is the exact opposite. What is clear is that the behavior of married black women has changed, to the point that married black women are actually having less kids than married white women.    

Coates is partially correct on this point.  The birth rate for married black women has fallen precipitously (between 1980 and 1998, it fell 26%, compared to 10% for unmarried black women).  Interestingly, the birth rate of married black women has now been eclipsed by that unmarried black women, something that has not happened in other groups that have seen similar trends.  I should note that here and elsewhere where I cite statistics, they all come straight from the CDC report linked to by Coates. The problem with Coates’ analysis is that it treats the married and unmarried populations as stable, and thus the differences in birth rates and the general trend upward in percentage of out-of-wedlock children (56% in 1980 compared to 70% now) stem entirely from behavioral changes, largely amongst married African-American women.  But these populations have not been stable, and this has been the social conservatives’ argument from the beginning: black women are avoiding marriage at a disproportionately high rate and having/raising the children they would have had with their husbands out-of-wedlock.  Further it is also not true, as Coates implies here, that this trend simply reflects couples not seeing the need to consecrate their union: the percentage of nonmarital births to cohabiting couples has remained at a little over 20% since 1980 for black mothers, while it has risen considerably for other groups in that same period. 

Assuming that population of married and unmarried women are not stable relative to each other, as is likely the case, also weakens Coates’ original rebuttal that the number of single mothers has not increased, relative to the general population.  But the statistic he cites from the CDC report is the number of nonmarital per every 1,000 single women.  All it demonstrates is that the pool of unmarried moms is growing slower than the pool of unmarried women generally, a scenerio that would be quite likely under a regime of total marital collapse.  It is thus very compatible with the notion that single motherhood is on the rise, provided that the number of unmarried women generally is growing even faster (indeed, the number of single black mothers has been regularly trending up in absolute terms since 1980).  Thus, Coates’ rebuttal is effectively meaningless and the high and growing percentage of children born out of wedlock remains as salient and distressing as it ever was.

Also, fun fact from one of the articles: gynecologists like to have their weekends off.   

An average of 11,338 infants were born each day in 2005. As in previous years, the average number of births was the highest on Tuesday (13,169), and the lowest on Sunday (7,374).  An index of occurrence can be used to measure the variation in the daily pattern of births. The index is defined as the ratio of the average number of births per day of the week to the average number of births per day of the year with the base set at 100. In 2005, Tuesday again had the highest index at 116.2, indicating that there were 16.2 percent more births on Tuesday than on the average day. Consistent with established patterns, infants in 2005 were much less likely to be born on weekends, with indices of occurrence of 74.6 for Saturday and 65.0 for Sunday.   

This weekend deficit is evident for both vaginal and cesarean deliveries, but is notably larger for cesarean births. Among births delivered by cesarean, the Tuesday index was 124.2 compared with a Sunday index of 47.0. Since 1989, when these data first became available, the weekend deficit for cesarean births has grown. Between 1989 and 2005, the Sunday index for cesarean deliveries fell 23 percent, from 60.7 to 47.0.  



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