Fertility and the puzzle of female employment in the Middle East and North Africa

Female labour force participation rates across the Middle East and North Africa (MENA) region have remained low for over four decades even though, in the same period, women's education rapidly increased and fertility rates substantially decreased. This study provides a better understanding of this surprising phenomenon by testing whether the number of children affects the mother's labour supply (using twins at first birth as an instrumental variable.) Despite a strong first stage, it does not find statistically significant effects in the second stage, even in the combined sample of over 100,000 observations. This non‐result, however, does not rule out that fertility affects women's employment in these countries. But it rejects impacts larger than 0.09. Similar twin‐studies in the United States found effects between 0.12 and 0.31. The paper discusses the implications of this result in understanding the puzzle of female participation in MENA and in designing policies to increase women's employment.     

Do Education and Income Really Explain Inequalities in Health? Applying a Twin Design

We apply a twin design to examine the relationship between health and education and income. The estimated associations between health and education and income, controlling for unobserved endowments, at the twin‐pair level, are lower than estimates obtained via ordinary least‐squares (OLS) on the same sample. Thus, OLS‐based effects of education and income are biased, exaggerating the contribution of education and income to health inequality. The main part of health inequality is explained by within‐twin‐pair fixed effects, incorporating family background and genetic inheritance. It appears that education and income policies have less to offer for reducing health inequality than is usually assumed.     

Better peers,better scores? A study of twin junior high school graduates in Taiwan

Using data of twin students graduating from junior high schools between 2002 and 2004 in Taiwan, we estimate the effects of peers on high school joint entrance examination performance. To alleviate the potential endogeneity of peer educational achievement, linear models with twin fixed effect and instrumental variables are estimated. Quantile, quantile with twin fixed effect and quantile with instrument variables regressions are also implemented to determine whether estimated peer effects differ at various locations of the testing scores’ conditional distributions. Positive and statistically significant peer effects are found to exist at the mean and at different quantile levels.     

Gender,Sibling Order,and Differences in the Quantity and Quality of Education: Evidence from Japanese Twins*

Using information on 1045 pairs of Japanese monozygotic twins, we examined differences in education by considering both the years of schooling (quantity) and the reputation of the last attended school (quality). We found that a difference in learning performance at 15 years of age is one of the key factors determining the differences. We also found that a female eldest child in the family from the 1950s and 1960s birth cohorts averaged 0.54 years less schooling than did her ‘younger’ twin. However, for the same birth cohorts, a male eldest child in the family generally had access to higher‐quality education than his ‘younger’ twin. Nonetheless, as the Japanese economy matured in the 1970s and thereafter, educational differences between twins disappeared, regardless of gender and sibling order.     

HETEROGENEITY OR TRUE STATE DEPENDENCE IN POVERTY: THE TALE TOLD BY TWINS

The purpose of this study is to distinguish between two different reasons that poverty could persist on an individual level. This study takes advantage of the similarity within pairs of identical twins to separate family‐specific heterogeneity from true state dependence, where the experience of poverty leads to a higher risk of future poverty. The results, based on a four‐variate probit model, show the importance of true state dependence in poverty. When using a poverty measure based on disposable income, family‐specific heterogeneity explains between 21 and 25 percent of poverty persistence in the Swedish sample of twins.     

Returns to Education Using a Sample of Twins: Evidence from Japan*

The objective of this article is to measure the causal effect of education on earnings using a large dataset of twins compiled in Japan with wide‐ranging socioeconomic information. Recent research conducted in China showed that, contrary to the case in Western countries, ability bias is large in estimating the return to education. It is argued that the low rate of return in China is in part due to the competitive and exam‐oriented education system, which is similar to the system in Japan. The empirical results in our study show that the estimated rate of return to education using the sample of identical twins in Japan is 9.3 percent even after omitted ability bias and measurement errors in self‐reported schooling were corrected. Our findings suggest that the conventional OLS estimate is not significantly contaminated by potential biases in Japan.     

基于决策融合的多卫星通信系统态势分析技术

为了解决高轨宽带、高轨移动、低轨星座卫星通信系统融合使用时，运行态势不全面、不精确等问题，设计了基于决策融合的多卫星通信系统态势分析技术。首先，借鉴数字孪生理论，建立板卡级、设备级、节点级、网络级、应用级5个层级体系化数字空间模型。其次，提取数据特征，得到高质量数据样本。最后，通过决策融合分析方法，对数据样本运用多种算法进行初步分析，再将不同算法的分析结果进行融合得出最终结果。结果表明，基于决策融合分析，能够对真实多卫星通信系统的不同指标主题得出较好的分析结果。因此，决策融合得到的分析结果可以帮助卫星通信系统运维人员更好地优化多卫星通信系统的运行状态。