Hypothesis testing for two population means: parametric or non-parametric test?

The parametric Welch $t$-test and the non-parametric Wilcoxon-Mann-Whitney test are the most commonly used two independent sample means tests. More recent testing approaches include the non-parametric, empirical likelihood and exponential empirical likelihood. However, the applicability of these non-parametric likelihood testing procedures is limited partially because of their tendency to inflate the type I error in small sized samples. In order to circumvent the type I error problem, we propose simple calibrations using the $t$ distribution and bootstrapping. The two non-parametric likelihood testing procedures, with and without those calibrations, are then compared against the Wilcoxon-Mann-Whitney test and the Welch $t$-test. The comparisons are implemented via extensive Monte Carlo simulations on the grounds of type I error and power in small/medium sized samples generated from various non-normal populations. The simulation studies clearly demonstrate that a) the $t$ calibration improves the type I error of the empirical likelihood, b) bootstrap calibration improves the type I error of both non-parametric likelihoods, c) the Welch $t$-test with or without bootstrap calibration attains the type I error and produces similar levels of power with the former testing procedures, and d) the Wilcoxon-Mann-Whitney test produces inflated type I error while the computation of an exact p-value is not feasible in the presence of ties with discrete data. Further, an application to real gene expression data illustrates the computational high cost and thus the impracticality of the non parametric likelihoods. Overall, the Welch t-test, which is highly computationally efficient and readily interpretable, is shown to be the best method when testing equality of two population means.Comment: Accepted for publication in the Journal of Statistical Computation and Simulatio

Exploring general practitioners’ views and experiences on suicide risk assessment and management of young people in primary care: a qualitative study in the UK

Objective: To explore general practitioner (GP) views and experiences of assessing, communicating with and managing suicidal young people with the aim of coproducing an educational intervention on youth suicide prevention tailored to GPs’ perceived needs. Design: Qualitative focus group study using framework analysis. Setting: 5 inner city general practices in Nottingham. Participants: 28 GPs took part (9 males) with mean age of 37 years. The median number of years of professional experience was 13. Participants were recruited through convenience sampling based on accessibility, interest in the study and willingness to participate. Results: 3 themes emerged from the data in relation to GP’s attitudes and beliefs towards suicide; the challenges GPs experience when it comes to the assessment and management of suicide risk in young people; and optimal ways of addressing some of these challenges through the provision of specialist education and training targeting GPs’ knowledge and clinical skills in this field. Conclusions: The findings revealed wide variations in the understanding and operationalisation of risk among GPs, which has subsequent implications to how GPs perceive risk should be assessed. GP education on suicide risk assessment and management in youth should promote a holistic understanding and assessment of risk and its individual, social and contextual influences

Truck Volume Estimation via Linear Regression Under Limited Data

This paper employs linear regression algorithms in order to train models under the presence of limited training data. Usually in transportation applications, these models are built via Ordinary Least Squares and Stepwise Regression, which perform poorly under limited data. The algorithms presented in this paper have been extensively used in other scientific fields for problems with similar conditions and seem to partially or fully remedy this problem and its consequences. Four different algorithms are presented and several models are built. The models are used for truck volume prediction on highway sections in New Jersey, and results are compared to Stepwise Linear regression models

Truck Volume Estimation via Linear Regression Under Limited Data

This paper employs linear regression algorithms in order to train models under the presence of limited training data. Usually in transportation applications, these models are built via Ordinary Least Squares and Stepwise Regression, which perform poorly under limited data. The algorithms presented in this paper have been extensively used in other scientific fields for problems with similar conditions and seem to partially or fully remedy this problem and its consequences. Four different algorithms are presented and several models are built. The models are used for truck volume prediction on highway sections in New Jersey, and results are compared to Stepwise Linear regression models

Truck Volume Estimation via Linear Regression Under Limited Data

This paper employs linear regression algorithms in order to train models under the presence of limited training data. Usually in transportation applications, these models are built via Ordinary Least Squares and Stepwise Regression, which perform poorly under limited data. The algorithms presented in this paper have been extensively used in other scientific fields for problems with similar conditions and seem to partially or fully remedy this problem and its consequences. Four different algorithms are presented and several models are built. The models are used for truck volume prediction on highway sections in New Jersey, and results are compared to Stepwise Linear regression models

Protocol for a systematic review and meta-analysis of cognitive-behavioural therapy for social anxiety disorder in psychosis

BACKGROUND: Social anxiety is among the most prevalent and debilitating affective disturbances manifest in people with psychosis. It is usually accompanied by high levels of depression and leads to significant social disability, lower quality of life and poorer prognosis as it raises the possibility of an early relapse. Despite its elevated prevalence and severity in psychosis, social anxiety remains under-recognized and under-treated. Cognitive-behavioural therapy is recommended for the treatment of people with psychosis. However, its focus and evaluation has primarily revolved around the reduction of psychotic symptoms, and not for co-morbid affective disturbances such as social anxiety. There is lack of evidence on the clinical effectiveness and cost-effectiveness of cognitive-behavioural interventions for the treatment of social anxiety disorder in psychosis. METHODS/DESIGN: Electronic databases will be systematically searched for randomised controlled trials and quasi-experimental studies investigating the effectiveness and cost-effectiveness of cognitive-behavioural interventions for the treatment of social anxiety disorder in people with psychosis. Grey literature will also be searched by screening trial registers. Only studies published in English will be included in the review. Date restrictions will not be applied. Eligible studies will have as the primary outcome social anxiety (continuous data) measured using any psychometrically validated scale both self-reported and clinician administered. Secondary outcomes will include general anxiety symptoms, distress, depression, positive and negative symptoms of schizophrenia, and quality of life measured using any psychometrically validated scale, both self-reported and clinician administered, and the cost of cognitive-behaviour therapy (CBT) intervention (with another treatment or treatment-as-usual). CONCLUSIONS: This review will provide an evidence synthesis of the effectiveness and cost-effectiveness of cognitive-behavioural interventions for the treatment of social anxiety disorder in people with psychosis. The review will identify the specific intervention components associated with effectiveness which will facilitate the translation of the existing evidence to the development of new, targeted interventions optimising these components. In doing so, this review will provide recommendations for the treatment of social anxiety and associated distress in psychosis and will further inform the development of future interventions in this area. TRIAL REGISTRATION: PROSPERO registration numberCRD42014009052

An overview of the mental health system in Gaza: an assessment using the World Health Organization’s Assessment Instrument for Mental Health Systems (WHO-AIMS)

Background: Mental health system reform is urgently needed in Gaza to respond to increasing mental health consequences of conflict. Evidence from mental health systems research is needed to inform decision-making. We aimed to provide new knowledge on current mental health policy and legislation, and services and resource use, in Gaza to identify quality gaps and areas for urgent intervention. Methods: As part of a mixed methods study, we used the World Health Organization’s Assessment Instrument for Mental Health Systems Version 2·2 to collect data on mental health services and resources. Data collection was carried out in 2011, based on the year 2010. Results: Gaza’s mental health policy suggests some positive steps toward reform such as supporting deinstitutionalisation of mental health services. The decrease in the number of beds in the psychiatric hospital and the progressive transition of mental healthcare toward more community based care are indicative of deinstitutionalisation. However, mental health legislation in support of deinstitutionalisation in Gaza is lacking. The integration of mental health into primary healthcare and general hospitals has not been fully achieved. Mental health in Gaza is underfunded, human rights protection of service users is absent, and human resources, service user advocacy, and mental health training are limited. Conclusion: Priority needs to be given to human rights protection, mental health training, and investment in human and organisational resources. Legislation is needed to support policy and plan development. The ongoing political conflict and expected increase in need for mental health services demonstrates an urgent response is necessary

Assessing Students’ Learning in MIS using Concept Mapping

The work described here draws on the emerging need to internationalize the curriculum in higher education. The focus of the study is on the evaluation of a Management Information Systems (MIS) Module, and the specification of appropriate course of action that would support its internationalization. To realize this goal it is essential to identify the possible learning needs of the two dominant cultural groups that compose the university student population in Britain, specifically European and Asian (UUK, 2005). Identification of knowledge patterns among these cultural groups is achieved through the application of a concept mapping technique. The main research questions addressed are: (1) How to internationalize the MIS module’s content and teaching methods to provide for students from different cultural backgrounds? (2) What are the main gaps in knowledge of students in MIS? The paper presents the results of this study and proposes actions needed to streamline the current teaching methods towards improving the quality of the students’ learning experience