A Generalization of the Univariate Slash by a Scale-Mixtured Exponential Power Distribution

A generalization of the slash distribution is derived using the scale mixture of the exponential power distribution. The newly defined family of distributions provides a rich flexibility on the tail heaviness and yields alternative robust estimators of location and scale in non normal situations. In order to investigate asymptotically the bias properties of the estimators, a simulation study is performed. The performance of the estimators on two well-known real data sets is also illustrated.     

Estimation of Change Point in Generalized Variance Control Chart

In this study, using maximum likelihood estimation, a considerably effective change point model is proposed for the generalized variance control chart in which the required statistics are calculated with its distributional properties. The procedure, when used with generalized variance control charts, would be helpful for practitioners both controlling the multivariate process dispersion and detecting the time of the change in variance-covariance matrix of a process. The procedure starts after the chart issues a signal. Several structural changes for the variance-covariance matrix are considered and the precision and the accuracy of the proposed method is discussed.     

Some factors affecting statistical power of approximate tests in the linear mixed model for longitudinal data

Different longitudinal study designs require different statistical analysis methods and different methods of sample size determination. Statistical power analysis is a flexible approach to sample size determination for longitudinal studies. However, different power analyses are required for different statistical tests which arises from the difference between different statistical methods. In this paper, the simulation-based power calculations of F-tests with Containment, Kenward-Roger or Satterthwaite approximation of degrees of freedom are examined for sample size determination in the context of a special case of linear mixed models (LMMs), which is frequently used in the analysis of longitudinal data. Essentially, the roles of some factors, such as variance–covariance structure of random effects [unstructured UN or factor analytic FA0], autocorrelation structure among errors over time [independent IND, first-order autoregressive AR1 or first-order moving average MA1], parameter estimation methods [maximum likelihood ML and restricted maximum likelihood REML] and iterative algorithms [ridge-stabilized Newton-Raphson and Quasi-Newton] on statistical power of approximate F-tests in the LMM are examined together, which has not been considered previously. The greatest factor affecting statistical power is found to be the variance–covariance structure of random effects in the LMM. It appears that the simulation-based analysis in this study gives an interesting insight into statistical power of approximate F-tests for fixed effects in LMMs for longitudinal data.     

Predicting online gambling self-exclusion: an analysis of the performance of supervised machine learning models

As gambling operators become increasingly sophisticated in their analysis of individual gambling behaviour, this study evaluates the potential for using machine learning techniques to identify individuals who used self-exclusion tools out of a sample of 845 online gamblers, based on analysing trends in their gambling behaviour. Being able to identify other gamblers whose behaviour is similar to those who decided to use self-exclusion tools could, for instance, be used to share responsible gaming messages or other information that aids self-aware gambling and reduces the risk of adverse outcomes. However, operators need to understand how accurate models can be and which techniques work well. The purpose of the article is to identify the most accurate technique out of four highly diverse techniques and to discuss how to deal analytically and practically with a rare event like self-exclusion, which was used by fewer than 1% of gamblers in our data-set. We conclude that balanced training data-sets are necessary for creating effective models and that, on our data-set, the most effective method is the random forest technique which achieves an accuracy improvement of 35 percentage points versus baseline estimates.     

Deleuze and the grandeur of Palestine: Song of Earth and Resistance

The article re-examines the Deleuzian concept of cartography and opens on the question of that race a fortiori minor called to philosophy and the constitution of an earth. Who are these people? Who are these people who, according to Deleuze, are missing? What is their name and what is their territory? The problem of minorities, “of the missing people”, analysed by Deleuze through Kafka finds a resonance and a quite particular affinity – and in this way a designation and a name – through the struggle of the Palestinian people; deterritorialized, “inferior, dominated, always becoming”. Deleuze’s pro-Palestinian engagement in no way manifests a rupture between philosophy and politics, but establishes itself as the essential correlate of a philosophically dynamic, creative and resistant reflection whose tenor has been constantly written into the realm of politics. After nearly 30 years, Deleuze’s pro-Palestinian positions are today the object of severe criticism, if not a cabal, launched by Eric Marty and Roger-Pol Droit, who aim at exhuming Deleuze’s philosophical corpus in order to extract from it a so-called “anti-Semitic complacency”.     

Postural assessment of school children: an input for the design of furniture

During the last decades of the previous century, school desks with a tilt top have disappeared. The chairs have been designed for sitting upright, with the hip, knees and ankles all at right angles. However, the erect posture cannot be maintained for more than one or two minutes, after which it will result in fatigue, discomfort or poor posture. The main aim of project is to identify the type of furniture that most effectively contribute to adequate neck and back postures of the school children, by carrying out a postural analysis of a sample of school pupils when using three different types of furniture. The postures adopted by school pupils were monitored by video during several activities, such as reading, writing and painting tasks, copying from a blackboard and listening the teacher. Additionally, the characteristics of the adopted postures were assessed by registering the head tilt, flexion of the neck, trunk and hips position. All these aspects were classified and the results were recorded for future analysis. The obtained results seem to point out that the use of a school desk with a tilted table surface resulted in a reduction in trunk and neck flexion, preserving the natural lordosis in the lumbar and cervical regions. Accordingly, it can be concluded that there are alternatives to consider in the furniture design in order to eliminate tensions and, consequently, to improve children's wellbeing.     

Physical and psychosocial indicators among office workers from public sector with and without musculoskeletal symptoms

Work-related musculoskeletal disorders (WRMD) are the result of the combination of different risk factors. They are very common among computer workers, mainly when neck and upper limbs are considered. Forty-two office workers from a public university participated in this study. They were divided into two groups: Symptomatic Subjects (SS, n=20) and Asymptomatic Subjects (AS, n=22), according to the Nordic Musculoskeletal Questionnaire (NMQ). Psychosocial indicators were assessed using the Job Content Questionnaire (JCQ) and Utrecht Work Engagement Scale (UWES). Workplaces were evaluated according to the Ergonomic Workplace Analysis (EWA), proposed by the Finnish Institute of Occupational Health. The NMQ showed higher weekly prevalence of complaints on neck, shoulders and wrist/hands (p=0.00) among SS. The annual prevalence of symptoms on wrist/hands was also higher among SS (p=0.02). The JCQ did not show any difference between groups (p>0.05). Higher proportion of servers with 'high level' of engagement, dedication and absorption, according to UWES, was identified among SS (p<0.01). EWA showed worse scores for 'Work Site', 'Job Content' and 'Repetitiveness of the Work' among SS (p<0.05). Servers are exposed to physical and psychosocial risk factors that can contribute to the development of WRMD. Work conditions need to be change in order to improve musculoskeletal health.