Suchergebnisse

A novel technique to analyze and visualize pandemic data and models is presented. Based on the fact that the system evolves in a loop (or two) in phase space, the path length and phase angle in the loop are relevant measures. In analogy to a complex physical system, the phase space for a pandemic consists of the variables (cases, deaths) and their derivatives or changes (new cases, new deaths). We focus on the new cases and new deaths variables. Both of these start out low (typically zero deaths and one or a few cases), rise to maximum values, and then reduce again to zero or low numbers if the pandemic wanes in the case of a periodic evolution. In the case of a second loop, the pattern repeats either with a higher or lower maximum value. The approach is illustrated for several regions of the world (e.g. Brazil, China, Germany, Pennsylvania, New York City, and New Jersey). In each case, our lognormal model is applied for reference purposes; however the computational analysis and visualization technique is model independent. Our approach to modeling the coronavirus pandemic using a lognormal solution to the differential equa- tions plus noise and primary harmonics is seen to work very well cross the entire spectrum of infection from lowest to highest mortalities. In the multiperiodic case, the pandemic will begin a second cycle as is seen in Pennsylvania and Louisiana. In the aperiodic case, no cycle is yet ap- parent: this may be the situation for the World, Brazil, and other states or countries until a loop is evident. Government officials can use these methods of analysis and visualization in real time to guide decisions about social and economic restrictions, where and when appropriate.

AbstractThe negative relationship between birth interval length and neonatal mortality risks is well documented, but heterogeneity in this relationship has been largely ignored. Using the Bangladesh Maternal Mortality and Health Care Survey 2010, this study investigates how the effect of birth interval length on neonatal mortality risks varies by maternal age at birth and maternal education. There is significant variation in the effect of interval length on neonatal mortality along these dimensions. Young mothers and those with little education, both of which make up a large share of the Bangladeshi population, can disproportionately benefit from longer intervals. Because these results were obtained from within‐family models, they are not due to unobservable heterogeneity between mothers. Targeting women with these characteristics may lead to significant improvements in neonatal mortality rates, but there are significant challenges in reaching them.

The western fertility decline is arguably the most significant demographic change to have occurred in the past 200 years, yet its causes and processes are still shrouded in ambiguity due to a lack of individual‐level longitudinal data. A growing body of research has helped improve our understanding of the decline's causes by examining the development of socioeconomic differences in fertility using historical micro‐data, but these have largely only considered rural areas where fertility was generally slower to decline. This article contributes to the literature by utilizing individual‐level data from the Roteman Database for Stockholm, Sweden between 1878 and 1926 to examine the association of socioeconomic status and fertility and the adoption of stopping behaviour during the city's transition. Using piecewise constant hazard models and logistic regression, we find that a clear class pattern arises in which the elite were early practitioners of fertility control, followed by the working classes. As the transition unfolded, socioeconomic differences in stopping behaviour disappeared and overall fertility differentials were also minimized, both of them being consistent with patterns observed in rural populations. The implications of these findings for major explanations of the decline are discussed in the concluding section.

AbstractEliminating child marriage is seen by policy makers and advocates as a path toward reducing births to girls below age 18, as most early births have been previously found to occur within marriage. There has been little recent evidence, however, of the marital context in which early childbearing occurs or how this relationship varies across space and levels of development. Using survey and vital registration data covering approximately 95 percent of the world's births to mothers younger than 18 years, we estimated the share of first births that occur within marriage at the global, regional and national levels. We found that more than half of births to mothers below age 18 worldwide take place in sub‐Saharan Africa, and this share will continue to grow. Globally, 76 percent of first births to mothers below age 18 occur within marriage and there are large regional differences. Over the past two decades, the share of first births to mothers below age 18 occurring within marriage declined in most countries with data available, but there are important exceptions. Although most first births to women below age 18 occur following seven months of marriage, the sequencing of child marriage and early childbearing varies widely across countries.