EFFECTS OF EXPOSURE ON PREVALENCE AND CUMULATIVE RELATIVE RISK: DIRECT AND INDIRECT EFFECTS IN A RECURSIVE HAZARD MODEL |
| |
Authors: | Lawrence L. Wu Steven P. Martin |
| |
Affiliation: | New York University; University of Maryland, College Park |
| |
Abstract: | This paper outlines decomposition methods for assessing how exposure affects prevalence and cumulative relative risk. Let x denote a vector of exogenous covariates and suppose that a single dimension of time t governs two event processes T 1 and T 2. If the occurrence of the event T 1 determines entry into the risk of the event T 2, then subgroup variation in T 1 will affect the prevalence T 2, even if subgroups in the population are otherwise identical. Although researchers often acknowledge this phenomenon, the literature has not provided procedures to assess the magnitude of an exposure effect of T 1 on the prevalence of T 2. We derive decompositions that assess how variation in exposure generated by direct and indirect effects of the covariates x affect measures of absolute and relative prevalence of T 2. We employ a parametric but highly flexible specification for baseline hazard for the T 1 and T 2 processes and use the resulting parametric proportional hazard model to illustrate the direct and indirect effects of family structure when T 1 is age at first sexual intercourse and T 2 is age at a premarital first birth for data on a cohort of non-hispanic white U.S. women. |
| |
Keywords: | |
|
|