7. Multivariate Decomposition for Hazard Rate Models

We develop a regression decomposition technique for hazard rate models, where the difference in observed rates is decomposed into components attributable to group differences in characteristics and group differences in effects. The baseline hazard is specified using a piecewise constant exponential model, which leads to convenient estimation based on a Poisson regression model fit to person-period, or split-episode data. This specification allows for a flexible representation of the baseline hazard and provides a straightforward way to introduce time-varying covariates and time-varying effects. We provide computational details underlying the method and apply the technique to the decomposition of the black-white difference in first premarital birth rates into components reflecting characteristics and effect contributions of several predictors, as well as the effect contribution attributable to race differences in the baseline hazard.

Better Child Support Enforcement

Stricter child support enforcement may reduce unwed childbearing by raising the costs of fatherhood. The authors investigate this hypothesis using a sample of young women from the National Longitudinal Survey of Youth, to which they add information on state child support enforcement. Models of the probability of a teenage premarital birth and of teenage premarital pregnancy and pregnancy resolution provide tentative evidence that during the early 1980s, teens living in states with higher rates of paternity establishment were less likely to become unwed mothers. This relationship is stronger for non-Hispanic Whites than for non-Hispanic Blacks. The findings suggest that policies that shift more costs of premarital child-bearing to men may reduce this behavior, at least among non-Hispanic Whites.