In the recent post on the fertility of wealthy white women, a reader raised the question of why conservative women have more children. He suggested it was greater religiosity and less involvement in the workplace.
We can use OLS regression analysis to help answer the question. I included white women ages 40-59 in households earning at least $100k in 1986 dollars. First, I regressed the number of offspring onto political orientation. The unstandardized coefficient is .161 (p < .05) which indicates that conservative women have significantly more babies. If we include church attendance, the coefficient drops to .120. If, instead, we include hours worked last week, the political coefficent drops to .132. If, instead, we include years of schooling completed, the political slope falls to .131. (The correlation between education and conservatism among wealthy white women is -.16--liberals tend to be more educated.) If all three controls are included in the model, the results look like this:
Number of offspring (sample size = 231)
Church attendance .098*
Hours of work -.007
*p < .05, two-tail
With the three controls included, the link between poltical views and number of offspring falls to non-significance. In this full model, number of hours worked also has no significant effect on fertility. To put it in plain English, the data indicate that wealthy white conservative women have more children because they are more religious and less educated than liberal women.
One caution: education's effect is not the influence of IQ. Among this demographic, IQ is unrelated to fertility. The correlation between IQ and number of kids is .02--basically zero. Education's influence appears to be cultural.