Minimal circular strongly balanced repeated measurements designs in periods of three different sizes

Repeated measurements designs (RMD) are widely used in medicine, pharmacology, animal sciences, and psychology. If there is a restriction on the total number of treatments, some experimental units can receive on the total length of time while some experimental units can remain in the trial, then RMD in periods of unequal sizes should be used. In this article, some infinite series are developed to generate the minimal circular strongly balanced RMD in periods of three different sizes p₁, p₂, and p₃, where 2 ≤ p₃ < p₂ ≤ 10.     

Simultaneous estimation of Cronbach’s alpha coefficients

The simultaneous estimation of Cronbachs alpha coefficients from q populations under the compound symmetry assumption is considered. In a multi-sample scenario, it is suspected that all the Cronbachs alpha coefficients are identical. Consequently, the inclusion of non-sample information (NSI) on the homogeneity of Cronbachs alpha coefficients in the estimation process may improve precision. We propose improved estimators based on the linear shrinkage, preliminary test, and the Steins type shrinkage strategies, to incorporate available NSI into the estimation. Their asymptotic properties are derived and discussed using the concepts of bias and risk. Extensive Monte-Carlo simulations were conducted to investigate the performance of the estimators.     

Performance of Kibria's Method for the Heteroscedastic Ridge Regression Model: Some Monte Carlo Evidence

It is common for a linear regression model that the error terms display some form of heteroscedasticity and at the same time, the regressors are also linearly correlated. Both of these problems have serious impact on the ordinary least squares (OLS) estimates. In the presence of heteroscedasticity, the OLS estimator becomes inefficient and the similar adverse impact can also be found on the ridge regression estimator that is alternatively used to cope with the problem of multicollinearity. In the available literature, the adaptive estimator has been established to be more efficient than the OLS estimator when there is heteroscedasticity of unknown form. The present article proposes the similar adaptation for the ridge regression setting with an attempt to have more efficient estimator. Our numerical results, based on the Monte Carlo simulations, provide very attractive performance of the proposed estimator in terms of efficiency. Three different existing methods have been used for the selection of biasing parameter. Moreover, three different distributions of the error term have been studied to evaluate the proposed estimator and these are normal, Student's t and F distribution.     

Transmuted Weibull distribution: Properties and estimation

In this article, we investigate the potential usefulness of the three-parameter transmuted Weibull distribution for modeling survival data. The main advantage of this distribution is that it has increasing, decreasing or constant instantaneous failure rate depending on the shape parameter and the new transmuting parameter. We obtain several mathematical properties of the transmuted Weibull distribution such as the expressions for the quantile function, moments, geometric mean, harmonic mean, Shannon, Rényi and q-entropies, mean deviations, Bonferroni and Lorenz curves, and the moments of order statistics. We propose a location-scale regression model based on the log-transmuted Weibull distribution for modeling lifetime data. Applications to two real datasets are given to illustrate the flexibility and potentiality of the transmuted Weibull family of lifetime distributions.     

Urban and peri-urban aquaculture as an immediate source of food fish: Perspectives of Dhaka City,Bangladesh

This paper describes the present status of aquaculture activities in Dhaka City and its surrounding areas including the system of fish marketing and distribution and environmental and socioeconomic issues. Dhaka City contains over 10 million people and is expanding day by day. Demand of fish in the last 10 years has increased as a result of increases in population and income levels. The annual per capita consumption of fish is reported to drop by 0.5 kg since 1985. The reason for this decline is increased prices and decreased supply of fish. Fish supply to the city comes from catch in the rivers-estuaries and floodlands of Dhaka district, neighboring districts, imports from other areas and aquaculture in surrounding areas of the city. Considerable quantities of fish are imported from India, Myanmar and Thailand. Seasonal patterns are common both in supply and consumption of fish. Along with traditional rural household aquaculture, in recent years, urban and peri-urban aquaculture has also been popular. Three broad types of aquaculture activities are found in and around Dhaka City; these are polyculture of carp in ponds, monoculture of catfishs in ponds, and pen and cage aquaculture in open waters. The carp includes both Indian major carp and Chinese carp and some minor carp. The catfish group includes mainly Thai pangas (Pangasius sutchi). Tilapia (Oreochromis niloticus) is also widely popular among the farmers. The technology used for aquaculture is improved extensive to semi-intensive. Increasing demand for fish in the city markets has encouraged the expansion of peri-urban aquaculture with a corresponding increase in the proportion of farmed fish in the markets.     

Inflation uncertainty and economic growth: evidence from the LAD ARCH model

In this paper, we combined the panel data and least absolute deviation autoregressive conditional heteroscedastic (ARCH) (L ₁-ARCH) model to infer on the relationship between inflation uncertainty and economic growth in five emerging market economies. Two interesting findings emerged from the analysis; first, we confirmed that the inflation uncertainty has a significant and negative effect on economic growth. Second, inflation is also an important variable and it is detrimental to economic prospects in the fast-growing Association of Southeast Asian Nations (ASEAN) economies. All in all, the empirical findings suggest that greater stability in the economy may be desirable in order to stimulate economic growth in the region.     

Population Growth and the Local Provision of Services: The Role of Primary Schools in Portugal

Population Research and Policy Review - The shrinking population in many European regions has led to a debate on the relation between the local provision of services of general interest and the...     

COVID‐19: A threat to educated Muslim women's negotiated identity in Pakistan

This study attempts to explore how the lockdown/containment measures taken by the government during the COVID‐19 pandemic have threatened educated Muslim women's negotiated identity regarding wifehood and motherhood in urban Pakistan and how they struggle to reposition to reconstruct it. Through semi‐structured interviews, making an in‐depth comparative study of three differently situated cases (Muslim women), this study argues that the abnormal situation that has ensued from the pandemic has reinforced the vulnerability of women's nascent negotiated identity by landing them in a space where they are supposed by the normative structures to step back to carrying out their traditional responsibilities as ‘good’ wife and mother during the crisis. It has found that the pandemic has similarity in its impacts for the women in their familial lives, despite their being variously situated and resistive, due to the general religio‐culturally defined patriarchal social behaviour of the place (Pakistan) toward women and lack of action on the part of the state for implementing its laws of women's empowerment.     

Two-step calibration of design weights under two auxiliary variables in sample survey

Calibration on the available auxiliary variables is widely used to increase the precision of the estimates of parameters. Singh and Sedory [Two-step calibration of design weights in survey sampling. Commun Stat Theory Methods. 2016;45(12):3510–3523.] considered the problem of calibration of design weights under two-step for single auxiliary variable. For a given sample, design weights and calibrated weights are set proportional to each other, in the first step. While, in the second step, the value of proportionality constant is determined on the basis of objectives of individual investigator/user for, for example, to get minimum mean squared error or reduction of bias. In this paper, we have suggested to use two auxiliary variables for two-step calibration of the design weights and compared the results with single auxiliary variable for different sample sizes based on simulated and real-life data set. The simulated and real-life application results show that two-auxiliary variables based two-step calibration estimator outperforms the estimator under single auxiliary variable in terms of minimum mean squared error.     

Estimation of multivariate frailty models with varying coefficients

The complicated structures can be modeled more efficiently and their flexibility can be increased through frailty models with varying coefficients.Therefore, such models are proposed in this article. The real challenge is to estimate varying coefficients by the penalized partial likelihood without closed form. The Laplace approximation is used to solve this problem. These varying coefficients are fitted using B-splines. Moreover, the variances of random effects are estimated by maximizing an approximate profile likelihood. The performance of the proposed methods are assessed with simulation studies and real data. The results show that the methods proposed are better than the counterpart in literature.