Testing goodness-of-fit for some lifetime distributions with conventional Type-I censoring

A goodness-of-fit test procedure is proposed for some lifetime distributions when the available data are subject to Type-I censoring. The proposed method extends the test procedure of Pakyari and Balakrishnan to other lifetime distributions. The extension to Weibull and log-normal models is studied in details. The new test recovers the nominal level of significance and exhibits more power in comparison to the existing tests for several alternative distributions by means of Monte Carlo simulations. Finally, a real dataset is considered for illustrative purposes.     

Young Adults' Fertility Expectations and Events: Associations With College Enrollment and Persistence

The analyses described in this article investigated the association between adolescent fertility expectations and college enrollment (N = 7,838). They also explored the potential impact of fertility expectations and events on college persistence among 4‐year (n = 2,605) and 2‐year (n = 1,962) college students. The analysis, which used data from the National Longitudinal Survey of Youth 1997 cohort, showed a significant association between expectations for early parenthood and the likelihood of going to a 4‐year college or 2‐year college for both men and women. In addition, the authors found that pregnancies were associated with an increased risk of college dropout for women; however, if all of the estimated effect of pregnancies on the risk of dropout were causal, they would still not be a major factor contributing to educational attainment because fertile pregnancies among college women are so rare.     

Designing an ergonomics backpack for student aged 7-9 with user centred design approach

Researches explored that backpacks are the most common means of carrying school supplies for students. Carrying heavy backpacks causes a wide range of disorders such as musculoskeletal disorders and postural malfunction. User Centered Design has proven its suitability to produce high efficient products with the most adaptability to consumer demands. This approach combined with consideration of normal standards and ergonomics features, with the recognition of children's needs and requirements, has been used in this research to prepare an initial design of a backpack. After that, its prototype was manufactured. The backpack was tested by 120 elementary students in three steps of form, ergonomics and load sense. A redesign was performed that has applied the results of the test run. Results showed that this new backpack can considerably reduce the effective loads on the shoulders, back and neck.     

‘Going Out’ or Staying In? The Expansion of Chinese NGOs in Africa

This article examines the overseas behaviour of Chinese non‐governmental organisations (NGOs) in two African nations, Ethiopia and Malawi, with varying political regime types. Our findings suggest that, irrespective of regime type, Chinese NGOs have yet to make a substantial impact in either nation. We argue that, despite the strength of the Chinese state and high levels of international development assistance given, domestic politics and regulatory frameworks in host nations still matter a great deal. Our study suggests that the Chinese model of international development will continue to be one in which temporary one‐off projects are favoured; and, insofar as social organisations will play a role, they will be in the domain of government‐organised NGOs rather than grassroots NGOs.     

Safe sets in graphs: Graph classes and structural parameters

A safe set of a graph \(G=(V,E)\) is a non-empty subset S of V such that for every component A of G[S] and every component B of \(G[V {\setminus } S]\), we have \(|A| \ge |B|\) whenever there exists an edge of G between A and B. In this paper, we show that a minimum safe set can be found in polynomial time for trees. We then further extend the result and present polynomial-time algorithms for graphs of bounded treewidth, and also for interval graphs. We also study the parameterized complexity. We show that the problem is fixed-parameter tractable when parameterized by the solution size. Furthermore, we show that this parameter lies between the tree-depth and the vertex cover number. We then conclude the paper by showing hardness for split graphs and planar graphs.     

Outsider ethnic minorities and wage determination in China

While some studies on urban ethnic minorities in China indicate that they earn lower wages relative to the Han majority, others show little evidence of this gap. To understand this contradiction, the authors propose that the primary issue is a failure to fully disaggregate ethnic minority groups’ labour market experiences. Leveraging a large data set looking at China's ethnic minorities, findings suggest that “outsider minorities”, such as Tibetans and Turkic groups, suffer a significant wage penalty when controlling for covariates, while minorities in aggregate do not. These findings are robust across various specifications and have notable theoretical and policy implications.     

A fractional version of the Cox–Ingersoll–Ross interest rate model and pricing double barrier option with Hurst index H∈(23,1)

In this work, we study the existence and uniqueness of the solution to a fractional version of the Cox–Ingersoll–Ross (fCIR) stochastic differential equation. The strong convergence of this equation is analyzed and according to it’s framework, we obtain the price of the double barrier option under transaction cost. Finally, we verify the effect of the parameters of the model on the value of the option.     

Lesbians and tech: Analyzing digital media technologies and lesbian experience

The rise of the popular Internet has coincided with the increasing acceptance, even assimilation, of lesbians into mainstream society. The visible presence of lesbians in the tech industry and in digitally mediated spaces raises a set of questions about the relationship between queer identities and Internet technologies. This introduction to a special issue of Journal of Lesbian Studies explores some of these questions and provides an overview of the articles that follow.     

A prior for the variance in hierarchical models

The choice of prior distributions for the variances can be important and quite difficult in Bayesian hierarchical and variance component models. For situations where little prior information is available, a ‘nonin-formative’ type prior is usually chosen. ‘Noninformative’ priors have been discussed by many authors and used in many contexts. However, care must be taken using these prior distributions as many are improper and thus, can lead to improper posterior distributions. Additionally, in small samples, these priors can be ‘informative’. In this paper, we investigate a proper ‘vague’ prior, the uniform shrinkage prior (Strawder-man 1971; Christiansen & Morris 1997). We discuss its properties and show how posterior distributions for common hierarchical models using this prior lead to proper posterior distributions. We also illustrate the attractive frequentist properties of this prior for a normal hierarchical model including testing and estimation. To conclude, we generalize this prior to the multivariate situation of a covariance matrix.