Exponentiated Teissier distribution with increasing,decreasing and bathtub hazard functions

This article introduces a two-parameter exponentiated Teissier distribution. It is the main advantage of the distribution to have increasing, decreasing and bathtub shapes for its hazard rate function. The expressions of the ordinary moments, identifiability, quantiles, moments of order statistics, mean residual life function and entropy measure are derived. The skewness and kurtosis of the distribution are explored using the quantiles. In order to study two independent random variables, stress–strength reliability and stochastic orderings are discussed. Estimators based on likelihood, least squares, weighted least squares and product spacings are constructed for estimating the unknown parameters of the distribution. An algorithm is presented for random sample generation from the distribution. Simulation experiments are conducted to compare the performances of the considered estimators of the parameters and percentiles. Three sets of real data are fitted by using the proposed distribution over the competing distributions.     

Underwriting and Calls of Convertible Bonds*

We model convertible bond calls under asymmetric information where, unlike Harris and Raviv (1985), we consider a nonzero call price and a call notice period. In the model, the use of underwriters conveys negative information. Consequently, the stock price decline is greater for underwritten calls than for nonunderwritten calls. Furthermore, underwritten calls are made earlier and when the conversion option is less deep in the money. Underwriting commissions and the stock price decline associated with a call are negatively related to the extent that the conversion option is in the money before the call. Empirical evidence in this paper and Singh, Cowan, and Nayar (1991) are consistent with the model's predictions.     

Environmental change and human mobility: Opportunities and challenges of big data

This paper explores the use of big data in understanding population movements in the context of environmental change, with particular attention to publicly available information from social media and newspapers. After discussing causal factors, the paper discusses the benefits and challenges of using big data, and mathematical models that may help capture the complexity of human mobility in the context of environmental change. We conclude that big data can be an important part of a toolkit in discerning drivers of migration and displacement. It is no panacea, however; the paper discusses potential problems in its use, particularly if big data are analysed to prevent people from moving out of harm's way. Therefore, partnerships between computer scientists and subject matter experts and practitioners are essential to ensuring that what is gathered from big data is usable, credible, and protects the privacy and rights of those who may be displaced.     

Projecting populations for major Pacific Island countries with and without COVID-19: pro-active insights for population policy

Journal of Population Research - The paper projects aggregate populations of six Pacific Island countries in both pre- and post-COVID19 scenarios using a Cohort Component Method for the period...     

Effects of face masks on language comprehension in bilingual children

Due to the COVID-19 pandemic, many children receive language input through face coverings. The impact of face coverings for children's abilities to understand language remains unclear. Past research with monolingual children suggests that hearing words through surgical masks does not disrupt word recognition, but hearing words through transparent face shields proves more challenging. In this study, we investigated effects of different face coverings (surgical masks and transparent face shields) on language comprehension in bilingual children. Three-year-old English-Mandarin bilingual children (N = 28) heard familiar words in both English and Mandarin spoken through transparent face shields, surgical masks, and without masks. When tested in English, children recognized words presented without a mask and through a surgical mask, but did not recognize words presented with transparent face shields, replicating past findings with monolingual children. In contrast, when tested in Mandarin, children recognized words presented without a mask, through a surgical mask, and through a transparent face shield. Results are discussed in terms of specific properties of English and Mandarin that may elicit different effects for transparent face shields. Overall, the present findings suggest that face coverings, and in particular, surgical masks do not disrupt spoken word recognition in young bilingual children.