Non-ignorable missing covariate data in survival analysis: a case-study of an International Breast Cancer Study Group trial

Summary.  Non-ignorable missing data, a serious problem in both clinical trials and observational studies, can lead to biased inferences. Quality-of-life measures have become increasingly popular in clinical trials. However, these measures are often incompletely observed, and investigators may suspect that missing quality-of-life data are likely to be non-ignorable. Although several recent references have addressed missing covariates in survival analysis, they all required the assumption that missingness is at random or that all covariates are discrete. We present a method for estimating the parameters in the Cox proportional hazards model when missing covariates may be non-ignorable and continuous or discrete. Our method is useful in reducing the bias and improving efficiency in the presence of missing data. The methodology clearly specifies assumptions about the missing data mechanism and, through sensitivity analysis, helps investigators to understand the potential effect of missing data on study results.     

Technical and vocational education and training in Uganda: A critical analysis

This article undertakes a diagnostic study of the Technical and Vocational Education and Training (TVET) sub‐sector in Uganda, with a view to characterizing the sub‐sector and identifying its potential strengths and weakness. We undertook a cross‐sectional pre‐survey of purposively selected key stakeholders in the TVET sub‐sector. We selected performance indicators following their importance in influencing the TVET reform process. Both qualitative and quantitative data was solicited from the stakeholders. Quantitative data was collected through stakeholder‐specific structured questionnaires, whilst qualitative data was collected through desk review and field visits, individual focused interviews and focus group discussions. Our findings indicate that financing and planning constraints have resulted in poor quality equipment, under‐ and ill‐trained staff, limited adoption of a competence‐based education and training (CBET) curriculum, not to mention the supervision inadequacies of TVET institutions. Besides, the limited TVET sub‐sector interaction with the private sector has incapacitated TVET curriculum development to nurture skills demanded by the private sector. Furthermore, backward technology use in the private sector has equally inhibited the success of student attachment programmes. Finally, legal ambiguities have perpetuated a qualification jungle and overlapping curricula.     

Understanding the Followers of Toxic Leaders: Toxic Illusio and Personal Uncertainty

Toxic leaders are one of the main threats to the wellbeing of people in the workplace and in society in general, and followers play a critical role in constructing and maintaining toxic leaders. In this narrative review, we draw on Bourdieu's concept of illusio and incorporate it with the social and cognitive psychology approaches in an attempt to frame the dynamic system that sustains toxic leadership through continued support of the followers. More specifically, as we introduce the illusio perspective in a process‐relational context to the toxic leadership discussion, we (i) address the allure of toxic leaders as an incentive for followers to join the toxic illusio as a way to cope with their high personal uncertainty and (ii) illustrate the mechanisms and processes that motivate followers of toxic leaders to remain in the toxic illusio once they join. In this context, we also briefly discuss and differentiate between the ethical and moral dimensions of toxic leadership.     

The Comparison of Performances of Widely Used Cointegration Tests

The aim of this study is to compare performances of commonly cointegration tests used in literature in terms of their empirical power and type I error probabilty for various sample sizes. As a result of the study, it has been found that some tests are not appropriate in testing cointegration in terms of empirical power and type I error probability. As a result of simulation study, λ_max test for any values of ρ and sample sizes have been found most appropriate test in conclusion.     

A new heavy-tailed distribution defined on the bounded interval: the logit slash distribution and its application

This paper proposes a new heavy-tailed and alternative slash type distribution on a bounded interval via a relation of a slash random variable with respect to the standard logistic function to model the real data set with skewed and high kurtosis which includes the outlier observation. Some basic statistical properties of the newly defined distribution are studied. We derive the maximum likelihood, least-square, and weighted least-square estimations of its parameters. We assess the performance of the estimators of these estimation methods by the simulation study. Moreover, an application to real data demonstrates that the proposed distribution can provide a better fit than well-known bounded distributions in the literature when the skewed data set with high kurtosis contains the outlier observations.     

Hard thresholding regression

In this paper, we propose the hard thresholding regression (HTR) for estimating high‐dimensional sparse linear regression models. HTR uses a two‐stage convex algorithm to approximate the ?₀‐penalized regression: The first stage calculates a coarse initial estimator, and the second stage identifies the oracle estimator by borrowing information from the first one. Theoretically, the HTR estimator achieves the strong oracle property over a wide range of regularization parameters. Numerical examples and a real data example lend further support to our proposed methodology.     

Challenges of implementing restorative justice for intimate partner violence: An Islamic perspective

ABSTRACT

Intimate partner violence (IPV) is currently recognized as a critical public health concern and a human rights issue. Not surprisingly, Muslims – a religiously and socio-culturally diverse faith-based populace – are not an exception. To address this complex area of criminal justice and social policy, some scholars advocate implementing restorative justice (RJ) approaches. While RJ approaches have been traditionally used in Islamic cultures for conflict resolutions, to date, few studies have investigated how RJ operates in dealing with IPV in Muslim countries and communities. This article explores how RJ approaches towards IPV operate in some Muslim countries/communities, and offers insights into developing culturally and religiously appropriate ways of implementing RJ in IPV situations among Muslims. Given the prevalence of IPV among Muslims, the question is particularly important and timely. Taking exclusively limited examples of RJ approaches that have been used to mediate IPV cases in Muslim countries and communities, this paper found one significant challenge in the RJ approaches among Muslims: community acceptance of IPV. To reduce IPV in Muslim society, it is necessary to develop treatment models and techniques that meet cultural and religious needs. This paper found that since RJ is not alien to Islamic teachings, RJ approaches can be implemented effectively in dealing with IPV among Muslims by ensuring justice and equity of the abused woman. The findings of this paper will assist policymakers, practitioners, and service providers in providing religiously and culturally appropriate care when addressing IPV issues among Muslims.     

Age and total and free prostate-specific antigen levels for predicting prostate volume in patients with benign prostatic hyperplasia

Objectives: To investigate the predictive values of free prostate-specific antigen (fPSA), total PSA (tPSA) and age on the prostate volume.

Methods: The data of 2148 patients with lower urinary tract symptoms were analyzed retrospectively. The patients who had transrectal ultrasonography guided 10 core biopsies owing to the findings obtained on digital rectal examination and presence of high PSA levels (PSA?=?2.5–10?ng/dl), and proven to have BPH histopathologically were included in the study. Age, tPSA, fPSA and the prostate volumes (PV) of the patients were noted.

Results: One thousand patients that fulfilled the inclusion criteria were included in the study. The PV of the patients were significantly correlated with age, tPSA and fPSA (p?r?=?0.307, p?r?=?0.382, p?r?=?0.296, respectively). On linear regression model, fPSA was found as a stronger predictive for PV (AUC?=?0.75, p?p?p?=?0.013).

Conclusions: Although tPSA is an important prognostic factor for predicting PV, the predictive value of fPSA is higher. PV can easily be predicted by using age, and serum tPSA and fPSA levels.     

Inverse Dynamic Data Envelopment Analysis for Evaluating Faculties of University with Quasi-Fixed Inputs

Social Indicators Research - Like other organizations, universities must evaluate their performance to identify areas for improvement. Although the different aspects of a university are considered...