The rising share of nonmarital births: Fertility choice or marriage behavior?

In a 2006 article in Demography, Jo AnnaGray Jean Stockard and Joe Stone (GSS i)observe that among black women and white women ages 20 to 39, birth rates increased sharply for unmarried women over the period 1974 to 2000. But they also increased for married women, as well, and yet the total birth rate for married and unmarried women combined was essentially unchanged; ii)conclude that’s since the total birth rate did not change, it seems obvious by inspection that the rises in unmarried and married birth rates could not have come from a general rise in fertility among women 20-39; iii)argue that these patterns are an example of a phenomenon called †Simpson’s paradox.,†often illustrated by a joke, as told at Harvard, that when a student transfers from Harvard to Yale, mean intelligence rises at both places. Both means rise not because the average intelligence of the combined student bodies changed, but because the composition of the student body changed at each school; iv) conclude that between 1974 and 2000, sharp increases in the proportion of women who were single, termed the single share, or Su, changed the composition of the pools of married and unmarried women. The rising single share had a selection effect on the pools of married and unmarried women akin to the hypothetical student transfer from Harvard to Yale. Women with target fertility below the average for married women, but above the average for unmarried women, became less likely to marry than previously, so that mean birth rates for both groups rose over the period, and iv) using age/race-specific panel data, find parameter values strikingly consistent with those predicted by their illustrative model, and a dominant role for the selection effect of the single share in determining the nonmaritalfertility tateErmisch Martin and Wu challenged the GSS findings and onclusions In this response,GSS response GSS repond to the challenges and reaffirm the GSS resuts and conclusions. JEL Categories: J12, J13, I38 F12; F23; H25