Inverse power Maxwell distribution: statistical properties,estimation and application

In this paper, we introduced a new probability distribution named as inverse power Maxwell distribution. The proposal distribution can be seen as an extension of the Maxwell distribution with more flexibility in modeling upside-down lifetime data. Some statistical properties of this distribution are derived. In estimation viewpoint, five methods are used for estimating the unknown parameters of the distribution and these methods are performed through the simulation study. Finally, two real data sets were analyzed to illustrate the applicability of the proposed distribution, proving that it fits each real data set much better than some other existing distributions.     

CDT-optimum designs for model discrimination, parameter estimation and estimation of a parametric function

After initiating the theory of optimal design by Smith (1918), many optimality criteria were introduced. Atkinson et al. (2007) used the definition of compound design criteria to combine two optimality criteria and introduced the DT- and CD-optimalities criteria. This paper introduces the CDT-optimum design that provides a specified balance between model discrimination, parameter estimation and estimation of a parametric function such as the area under curve in models for drug absorbance. An equivalence theorem is presented for the case of two models.     

On statistical tests of functional connectome fingerprinting

Fingerprinting of functional connectomes is an increasingly standard measure of reproducibility in functional magnetic resonance imaging connectomics. In such studies, one attempts to match a subject's first session image with their second, in a blinded fashion, in a group of subjects measured twice. The number or percentage of correct matches is usually reported as a statistic, which is then used in permutation tests. Despite the simplicity and increasing popularity of such procedures, the soundness of the statistical tests, the power, and the factors impacting the test are unstudied. In this article, we investigate the statistical tests of matching based on exchangeability assumption in the fingerprinting analysis. We show that a nearly universal Poisson(1) approximation applies for different matching schemes. We theoretically investigate the permutation tests and explore the issue that the test is overly sensitive to uninteresting directions in the alternative hypothesis, such as clustering due to familial status or demographics. We perform a numerical study on two functional magnetic resonance imaging (fMRI) resting‐state datasets, the Human Connectome Project (HCP) and the Baltimore Longitudinal Study of Aging (BLSA). These datasets are instructive, as the HCP includes technical replications of long scans and includes monozygotic and dizygotic twins, as well as non‐twin siblings. In contrast, the BLSA study incorporates more typical length resting‐state scans in a longitudinal study. Finally, a study of single regional connections is performed on the HCP data.     

Estimation of the coefficient of variation for non-normal model using progressive first-failure-censoring data

The coefficient of variation (CV) is extensively used in many areas of applied statistics including quality control and sampling. It is regarded as a measure of stability or uncertainty, and can indicate the relative dispersion of data in the population to the population mean. In this article, based on progressive first-failure-censored data, we study the behavior of the CV of a random variable that follows a Burr-XII distribution. Specifically, we compute the maximum likelihood estimations and the confidence intervals of CV based on the observed Fisher information matrix using asymptotic distribution of the maximum likelihood estimator and also by using the bootstrapping technique. In addition, we propose to apply Markov Chain Monte Carlo techniques to tackle this problem, which allows us to construct the credible intervals. A numerical example based on real data is presented to illustrate the implementation of the proposed procedure. Finally, Monte Carlo simulations are performed to observe the behavior of the proposed methods.     

Plant species distribution and spatial habitat heterogeneity in the landscape of urbanizing desert ecosystems in Egypt

Information on the urban flora and vegetation in the industrial new cities in Egypt are insufficient and far from complete. For this reason, this study was undertaken as the first attempt to fill this gap of knowledge. For two successive years (2004 and 2005), a reconnaissance survey was conducted in four new industrial cities: 6th October, El-Sadat, Burg El-Arab and 10th Ramadan; aiming at: (1) recognizing the floristic composition and vegetation structure of each of the studied cities; (2) identifying the main urban habitats dominating the studied cities; (3) comparing the vegetation of the urban habitats at the boundaries of each city, where desert soil merges gradually with the agricultural land, with that at its centre (purely agricultural land); and (4) analyzing, quantitatively, the vegetation groups (plant communities) that characterize the urban habitats. A total of 189 permanent stands in the four cities were selected to represent the apparent variation in the different habitats. These stands were distributed as follows: 49 in 6th October, 37 in El-Sadat, 45 in Burg El-Arab, and 58 in 10th Ramadan. Altogether, 305 species of the vascular plants constituted the main synanthropic flora and the total number of species varied from 171 in Burg El-Arab, 157 in 10th Ramadan, 144 in Sadat and 132 to 6th October. The largest families that formed the main bulk of the recorded flora were Gramineae, Compositae, Leguminosae, followed by Euphorbiaceae, Chenopodiaceae, Cruciferae, Cyperaceae, Umbelliferae and Solanaceae. Five main urban habitats (from inner city toward outskirts) were distinguished: lawns, home gardens, public gardens, waste lands and desert outskirts. The most species-rich habitat was the waste lands (172 species), while the total number of species varied from 104 in the lawns and 113 home gardens, to 123 in the desert and 133 in the public gardens. Generally, the recorded synanthropic flora within the five main urban habitats can be classified into: (1) cultivated plant species that included ornamentals, hedges, shade plants, fodder plants, vegetables and fruits; (2) canal banks, salinized areas and wetland plants; (3) xerophytic plants of the outskirting desert; and (4) weeds of arable lands. Application of multivariate analyses techniques to 4 floristic data matrices yielded 22 TWINSPAN vegetation groups in the cities, and 26 in the five habitats, clearly separated along the first two axes of DCA.     

Moments of order statistics from doubly truncated continuous distributions and characterizations

In this paper, recurrence relations from a general class of doubly truncated continuous distributions which are satisfied by single as well as product moments of order statistics are obtained. Recurrence relations from doubly truncated generalized Weibull, exponential, Raleigh and logistic distributions have been derived as special cases of our result, Some previous results for doubly truncated Weibull, standard exponential, power function and Burr type XII distributions are obtained as special cases. The general recurrence relation of single moments has been used in the case of the left and right truncation to characterize the Weibull, Burr type XII and Pareto distributions.     

Undoing Islamophobia: Awareness of Orientalism in Social Work

Islamophobia describes the racism, exploitation, and violence experienced by Arabs, individuals of Arab descent, and Muslims. Although social workers are meant to challenge social injustice, social work codes of ethics and the literature are without guidance for unlearning Islamophobia. Arguing that one’s ability to interrupt Islamophobia is strengthened by an understanding of the historical record and theoretical tenets of Orientalism, we offer social workers explicit linkages between Orientalism and Islamophobia and engage with the idea of Islamo-racism. In this article, we attend to the ways in which Orientalism is used to “other” individuals while strengthening white hegemony, and we link those processes with Islamophobia and Islamo-racism. We conclude with some strategies derived from postcolonial theory to disrupt Islamophobia.     

A Parametric Model for the Interval Censored Survival Times of Acacia Mangium Plantation in a Spacing Trial

Survival times for the Acacia mangium plantation in the Segaliud Lokan Project, Sabah, East Malaysia were analysed based on 20 permanent sample plots (PSPs) established in 1988 as a spacing experiment. The PSPs were established following a complete randomized block design with five levels of spacing randomly assigned to units within four blocks at different sites. The survival times of trees in years are of interest. Since the inventories were only conducted annually, the actual survival time for each tree was not observed. Hence, the data set comprises censored survival times. Initial analysis of the survival of the Acacia mangium plantation suggested there is block by spacing interaction; a Weibull model gives a reasonable fit to the replicate survival times within each PSP; but a standard Weibull regression model is inappropriate because the shape parameter differs between PSPs. In this paper we investigate the form of the non-constant Weibull shape parameter. Parsimonious models for the Weibull survival times have been derived using maximum likelihood methods. The factor selection for the parameters is based on a backward elimination procedure. The models are compared using likelihood ratio statistics. The results suggest that both Weibull parameters depend on spacing and block.