Do more-schooled women have fewer children and delay childbearing? Evidence from a sample of US twins

Using data on monozygotic (MZ) (identical) female twins from the Minnesota Twin Registry, we estimate the causal effect of schooling on completed fertility, probability of being childless, and age at first birth using the within-MZ twins methodology. We find strong cross-sectional associations between schooling and the fertility outcomes, and some evidence that more schooling causes women to have fewer children and delay childbearing, though not to the extent that interpreting cross-sectional associations as causal would imply. Our conclusions are robust when taking account of (1) endogenous within-twin pair schooling differences due to reverse causality and (2) measurement error in schooling. We also investigate possible mechanisms and find that the effect of women’s schooling on completed fertility is not mediated through husband’s schooling but may be mediated in part through age at first marriage.     

How Islamic Has the “Islamic State” Been?

Two principal views have emerged on the nature and operations of the so-called Islamic State or khilafat. One contends that IS had nothing to do with Islam in both its ideological disposition and practical operations. The other view claims that IS was the embodiment of a Salafist?Wahhabi version of Islam, and therefore it was Islamic. Whereas the first view recognizes the fact that Islam like any divine faith is open to a range of interpretations and applications, the second perspective has treated Islam as a monolithically adaptable doctrine, ignoring the diversity within the Muslim world. The question is: Was IS Islamic or not, or did it exude a form of political Salafism and Islamism of our time?     

A New Test of Randomness for Lehmer Generators Based on the Manhattan Distance Between Pairs of Consecutive Random Numbers

This article considers the Marsaglia effect by proposing a new test of randomness for Lehmer random number generators. Our test is based on the Manhattan distance criterion between consecutive pairs of random numbers rather than the usually adopted Euclidian distance. We derive the theoretical distribution functions for the Manhattan distance for both overlapping (two dimensional) as well as non-overlapping cases. Extensive goodness-of-fit testing as well as empirical experimentation provides ample proof of the merits of the proposed criterion.     

Bayesian identification of double seasonal autoregressive time series models

ABSTRACT

Seasonal autoregressive (SAR) models have been modified and extended to model high frequency time series characterized by exhibiting double seasonal patterns. Some researchers have introduced Bayesian inference for double seasonal autoregressive (DSAR) models; however, none has tackled the problem of Bayesian identification of DSAR models. Therefore, in order to fill this gap, we present a Bayesian methodology to identify the order of DSAR models. Assuming the model errors are normally distributed and using three priors, i.e. natural conjugate, g, and Jeffreys’ priors, on the model parameters, we derive the joint posterior mass function of the model order in a closed-form. Accordingly, the posterior mass function can be investigated and the best order of DSAR model is chosen as a value with the highest posterior probability for the time series being analyzed. We evaluate the proposed Bayesian methodology using simulation study, and we then apply it to real-world hourly internet amount of traffic dataset.     

Improved switching rules in control procedures using variable sampling intervals

Some properties of control procedures with variable sampling intervals (VSI) have been investigated in recent years by Amin, Renolds et al, and others. Such procedures have been shown to be more efficient when compared to the corresponding fixed sampling interval (FSI) charts with respect to the Average Time to Signal (ATS) when the Average Run Length (ARL) values for both types of procedures are held equal. Frequent switching between the different sampling intervals can be a complicating factor in the application of control charts with variable sampling intervals (VSI). This problem is being addressed in this article, and improved switching rules are presented and evaluated for Shewhart, CUSUM, and EWMA control procedures. The proposed rules considerably reduce the average number of switches between the sampling intervals and also improve the ATS properties of the control procedures when compared to the conventional variable sampling interval procedures     

Ratio- and difference-type estimators for estimating finite population variance

We consider the problem of estimating finite population variance of a study character when information on an auxiliary character is available. We define ratio- and difference-type estimators and obtain the mean-squared error of them approximately. Using a numerical study, we compare the performances of the proposed estimators with some existing variance estimators.     

Emphasizing the experiences of researchers after RCR instructions: Introduction to Responsible Conduct of Research (RCR) in Malaysia

The purpose of this study is to highlight the experiences of individuals who participate in the Responsible Conduct of Research (RCR) training program held at various universities in Malaysia. In response to a mailing request sent to 40 individuals who had undertaken a RCR training program, 15 participants agreed to be interviewed. The results of the study showed that the three main reasons for participating in the training were as follows: anticipation for knowledge gained; personal experience with research misconduct; and establishing a new network of researchers. In terms of the positive effects gained from undertaking the training, the participants highlighted an increased awareness of the issues and problems related to research misconduct; the need to promote integrity in research conduct; a change in the way they conduct their research; and a change in the way they confront and address misconduct. The findings of this study should be valuable for policy makers and those involved in the management of research programs and ethics, as it demonstrated the importance of RCR training in equipping researchers with the necessary knowledge to conduct research responsibly, and to avoid research misconduct.     

The Multi-dimensional Effect of Household Debt on Urban Individual Well-Being in Klang Valley Malaysia

Social Indicators Research - Debt is beneficiary to individuals and households when their consumption can be extended with credit. However, the benefits gained from availability of credit have...