Quantifying the Family Frailty Effect in Infant and Child Mortality by Using Median Hazard Ratio (MHR)

Most microlevel studies in the social sciences have focused on the impact of different measured variables. While some studies have also dealt with unobserved variation, it has usually only been controlled for to perfect the estimates of the observables. In this article, the authors applied a modified version of a recently developed method designed to quantify the effect of unobserved variation in continuous time multilevel models, called a median hazard ratio. It allows a direct comparison of the effect of unobserved heterogeneity with standard relative risks. The method is used in an analysis of infant and child mortality in southern Sweden during the period 1766-1895. The empirical findings indicate that unmeasured differences between families were more important than either socioeconomic status or gender throughout this period.