Migration and marriage: Modeling the joint process

AbstractBACKGROUNDPrevious research on interrelations between migration and marriage has relied on overly simplistic assumptions about the structure of dependency between the two events. However, there is good reason to posit that each of the transitions has an impact on the likelihood of the other, and that unobserved common factors may affect both migration and marriage, leading to a distorted impression of the causal impact of one on the other.OBJECTIVEWe will investigate the relationship between migration and marriage in the United States, using data from the National Longitudinal Survey of Youth 1979. We allow for interdependency between the two events and examine whether unobserved common factors affect the estimates of both migration and marriage.METHODSWe estimate a multi-process model in which migration and marriage are considered simultaneously in regression analysis and there is allowance for correlation between disturbances; the latter feature accounts for possible endogeneity between shared unobserved determinants. The model also includes random effects for persons, exploiting the fact that many people experience both events multiple times throughout their lives.RESULTSUnobserved factors appear to significantly influence both migration and marriage, resulting in upward bias in estimates of the effects of each on the other when these shared common factors are not accounted for. Estimates from the multi-process model indicate that marriage significantly increases the hazard of migration, while migration does not affect the hazard of marriage.CONCLUSIONSOmitting interdependency between life course events can lead to a mistaken impression about the direct effects of certain features of each event on the other.1. IntroductionMigration decisions are made in conjunction with decisions about other life course events (Groot, Mulder, Das, and Manting 2011; Kulu and Milewski 2007; Schachter 2001). For example, when young adults leave the parental home and settle in new places in order to pursue educational and occupational opportunities (Garasky, Haurin, and Haurin 2001), some will find partners there and form families (Kulu 2008). Changes in union status (formation or dissolution) and childbearing can also motivate changes in residence, in part due to space requirements (Flowerdew and Al-Hamad 2004; Kulu and Milewski 2007). These and other plausible life course scenarios suggest an interplay between migration and other life course transitions that is far from unidirectional (Kulu and Milewski 2007). Nevertheless, most empirical research to date has examined unidirectional effects only. This has certainly been the case with research on migration and marriage, most of which has simplified the role of the former, with migration serving as an explanatory variable that either promotes or delays union formation (Feijten and Mulder 2002; Guzzo 2006). However, we suspect that the relationship between migration and marriage is more complicated. It is plausible that migration affects marriage and marriage affects migration; ignoring this more complicated interdependency may yield biased estimates of the causal effects of interest, including the effects of other explanatory variables - for example, schooling history (Mulder and Wagner 1993; Kulu and Milewski 2007; Steele, Kallis, Goldstein, and Joshi 2005). In addition, selectivity could be an issue - for example, migrants could be persons who are prone to marry, or vice versa (Kulu and Milewski 2007; Mulder and Wagner 1993).Despite these concerns, the comprehensive set of plausible interrelations between migration and marriage has hardly been examined in empirical research to date. And the few studies that have considered this range of interrelations have relied on data from Europe (Michielin and Mulder 2008). While it may be reasonable to draw implications for the interdependency in the United States from findings in European countries, it is the case that migration and marriage in the U. …