Orientation relationship in finite dimensional space

In the present article, we discuss the regression of a point on the surface of a unit sphere in d dimensions given a point on the surface of a unit sphere in p dimensions, where p may not be equal to d. Point projection is added to the rotation and linear transformation for regression link function. The identifiability of the model is proved. Then, parameter estimation in this set up is discussed. Simulation studies and data analyses are done to illustrate the model.     

On an application of the diffusion approximation of the generalized birth and death process for stochastic population projection

Assuming that both birth and death rates are density and time dependent, a diffusion approximation of the generalized birth and death process has been considered in this paper to obtain a suitable stochastic population model describing the population size and its moments. A simple method of estimating the parameters of the model Is discussed. The predictions of the expected size of the population, and the variance are made and compared with the corresponding census figures as well as with another deterministic projection series made for the corresponding period.     

Designs Robust against Violation of Normality Assumption in the Standard F-test

In this article, designs are found for which the F-test of analysis of variance is insensitive to violation of normality assumption. Atiqullah (1962 Atiquallah, M. (1962). The estimation of residual variance in quadratically balanced least-squares problems and the robustness of the F-test. Biometrika 49: 83–91.[Crossref], [Web of Science ®] , [Google Scholar]) proved that the F-test for treatments adjusting for blocks in the intra-block analysis of a balanced incomplete block design is robust against non-normality in the observations. Here an attempt has been made to identify other designs robust in this sense. In particular, it is observed that for testing relevant hypothesis, a partially balanced incomplete block design in block design setup, under certain conditions, is robust. Robustness of a balanced treatment incomplete block design and a partially balanced treatment incomplete block design (Biswas, 2012 Biswas, A. (2012). Block designs robust against the presence of an aberration in a treatment-control setup. Commun Statist.Theor Methods 41: 920–933.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]), in treatment-control design setup, is also studied. Moreover, a new measure of robustness is introduced for further study. The performance of the F-test in presence of non-normality in the observations for a quadratically balanced design is also examined.     

The segregative properties of endogenous formation of jurisdictions with a welfarist central government

This paper examines the segregative properties of Tiebout-type process of jurisdiction formation by freely mobile households in the presence of a central government which makes equalization transfers across jurisdictions so as to maximize a generalized utilitarian or a max–min objective. It is shown that the introduction of such a central government significantly affects the set of stable jurisdiction structures. It is also shown that the class of households additively separable preferences that guarantees the wealth segregation of any stable jurisdiction structure is unaffected by the presence of a central government if this government uses a generalized utilitarian objective.     

Extreme quantile estimation based on financial time series

Estimation of market risk is an important problem in finance. Two well-known risk measures, viz., value at risk and median shortfall, turn out to be extreme quantiles of the marginal distribution of asset return. Time series on asset returns are known to exhibit certain stylized facts, such as heavy tails, skewness, volatility clustering, etc. Therefore, estimation of extreme quantiles in the presence of such features in the data seems to be of natural interest. It is difficult to capture most of these stylized facts using one specific time series model. This motivates nonparametric and extreme value theory-based estimation of extreme quantiles that do not require exact specification of the asset return model. We review these quantile estimators and compare their known properties. Their finite sample performance are compared using Monte Carlo simulation. We propose a new estimator that exhibits encouraging finite sample performance while estimating extreme quantile in the right tail region.     

Causes of Urban Migration in Bangladesh: Evidence from the Urban Health Survey

Mass migration is increasing urban populations globally. One country where urban migration is significantly increasing is Bangladesh, where systematic research will explore the reasons for urban migration in order to devise policies in this area, including maintaining the balance of urban–rural developments. This study used the Urban Health Survey (UHS) 2013 to ascertain the reasons for urban migration in large divisional cities in Bangladesh. The 2013 survey examined the differences between male and female migration, alongside any significant sociodemographic factors that might contribute to their motivation for moving to the city. The survey revealed that a majority of women (64.8%) migrated for family purposes, for example, joining husbands or in-laws, or parents/children. However, in recent years, female migrants have been involved in income-generating activities mostly due to a recent garment-making boom in Dhaka and its suburbs. A higher proportion of men (85.3%) moved to urban areas for work-related reasons: searching for new jobs, better income, or transfer in services. Among the sample in this study, 77% of the respondents (79.3% female and 73.5% male) migrated from villages. This migration mostly centered on Dhaka, the capital city of Bangladesh, where 68.1% of the total study sample migrated followed by 15.7% who went to Chittagong. The results indicate that the contemporary urban-centered economic policy in Bangladesh might require revision to accommodate the increased migrants from rural areas.

     

Measures of association for nominal categorical variables

This paper reviews existing measures of association for nominal categorical variables, and presents some alternative measures of association, which are symmetric and flexible enough to find partial and multiple association.     

A general adaptive allocation design for continuous responses in the presence of covariates

Several adaptive allocation designs are available in the clinical trial literature for allocating the entering patients among two competing treatments, having binary responses and skewing the allocation in favor of the better treatment. No adaptive design is available for continuous responses in the presence of prognostic factors, which is not model based. In the present paper, a general allocation design is introduced which assumes no specific regression model or distribution of responses. Some performance characteristics of the design are studied. Some related inference, following the allocation, is also studied. The proposed procedure is compared with some possible competitors. A real data set is used to illustrate the applicability of the proposed design.     

“Isn't it ironic…!?!” Mobility researchers go sedentary: A group auto-ethnography on collective coping and care in pandemic times

We moved places and places moved us, until force majeure detained us on the spot. Signed-up to be hyper-mobile Ph.D.-candidates, we became hyper-reflective pandemic intimates. We moved together into a space that felt safe, OUR safe space. Suspended. Did the pandemic open this door, or had this space always existed, even back in the old days? Probably the latter, although we were not sensitive enough to perceive it, too busy to push the door, too lonesome to CARE. Not attentive to its possibilities, not imaginative of its POWER, too confident to be capable of succeeding alone. Even if we might have secretly wished for this space to exist. The present piece of work, and JOY, might be described by others as a “side-step,” a “hobby project,” a “shadow activity.” For us, it is a recollection of shocks and wonders, a sentience of precious, ephemeral instances that last. We are a group of eight early career researchers who study global mobility and labor migration from a variety of disciplinary perspectives. With prior international mobility experience, we left our previous countries of residence in 2018 to join an EU-funded research project, whilst being located in different European cities. One could classify us, for example, as highly qualified, privileged migrants. The present paper is the outcome of a collaborative, auto-ethnographic study, conducted in 2020, in the midst of the Covid-19 pandemic, when we suddenly were forced not to travel anymore. We got together online every week to “refaire le monde,” and we conducted virtual, dialogical self-interrogations and group reflections. Based on an emic approach, in line with Chang et al. (2013), we applied an iterative process of data collection and analysis. Our weekly conversations naturally emerged as a safe space for exchange and understanding, as we were facing similar situations, despite staying at different places. Suddenly, as the privilege of “always being on the move,” “always socializing and networking” disappeared due to closed borders and pandemic threats, we experienced anxieties and isolation and had to re-evaluate our perceptions on life, work, and international mobility. The very purpose and meaning of our broader research endeavors and employment perspectives suddenly faded away. We realized more than ever before, what it means to us to be allowed to move, to travel freely across continents.