Reliability and validity in comparative studies of software prediction models

Empirical studies on software prediction models do not converge with respect to the question "which prediction model is best?" The reason for this lack of convergence is poorly understood. In this simulation study, we have examined a frequently used research procedure comprising three main ingredients: a single data sample, an accuracy indicator, and cross validation. Typically, these empirical studies compare a machine learning model with a regression model. In our study, we use simulation and compare a machine learning and a regression model. The results suggest that it is the research procedure itself that is unreliable. This lack of reliability may strongly contribute to the lack of convergence. Our findings thus cast some doubt on the conclusions of any study of competing software prediction models that used this research procedure as a basis of model comparison. Thus, we need to develop more reliable research procedures before we can have confidence in the conclusions of comparative studies of software prediction models

Academics' Role and Relevance in National Development. The Case of Engineers at Makerere University in Uganda

This thesis is a case study of engineers at Makerere University in Uganda. In a broad sense the thesis explores the relationship between scientific knowledge and development in a low-income, Sub-Saharan country, which is yet to be industrialised. There is a prevailing optimism towards the hard sciences, such as engineering, and its potential contributions to development and industrialization. Yet, we know from previous literature that there are many challenges for the sub-Saharan universities, related to funding, lack of facilities, brain drain but also related to their respective government. The aim of the study is to get a deeper understanding of the role of academics and scientific knowledge in the national development agenda. The research question for the thesis is ‘how do the engineers at Makerere University perceive the relevance of their knowledge to national development and industrialisation of Uganda?’. To answer this research question, data was collected through semi-structured interviews with 20 academics affiliated to the School of Engineering, at Makerere University. My findings show that there is a large variation among the engineering academics at Makerere University and how they understand and fulfil their role at the university. Where previous studies have tended to treat academics as a unanimous group, this study shows how a group of academics within the same college vary in motivations, aspirations and how this affects the work they do at the University and thus the relevance of their knowledge to national development. However, there are several challenges for the academics to contribute on the same level as their colleagues in other countries. The strong dependency on international donors of funding for research does not only limit the academics’ ability to do research, but it also has consequences for the academics’ ability to decide areas of research and thus define their own research questions. This makes it difficult for the academics to address issues of national concern, thus the national development agenda.Masteroppgave i administrasjon og organisasjonsvitenskapAORG350MASV-AOR

Risk factors for development and maintenance of chronic whiplash

Background: After experiencing whiplash accidents, most individuals recover rapidly. Others, however, develop chronic whiplash, a condition characterized by long lasting neck pain, somatic complaints and symptoms of anxiety and depression. Individuals with chronic whiplash report the condition to reduce their quality of life and ability to work. As most individuals recover from whiplash accidents without needing medical attention, identifying those at risk of chronic complaints, and in need of treatment, is important. Factors related to the whiplash accident, like speed and extent of damage to the cars, as well as findings from clinical imaging seem poorly correlated with outcome. Previous research indicates that socio-demographic factors, pre-injury somatic and mental health as well as coping might be associated with prognosis. However, as existing literature remains inconclusive, and much of the research is based on retrospectively collected data, more evidence is needed. Aim: The overall aim of the thesis was to investigate whether socio-demographic factors, pre- and post-injury health, use of health care and medications, and early coping preferences are associated with outcome after whiplash accidents. Method: In study one and two data from two waves of the large, Norwegian population-based Nord-Trøndelag Health Study (HUNT2 and HUNT3) was used. Study one investigated whether socio-demographic variables (such as age, gender, education) and health related variables (such as perceived health, health behavior and use of health-services, musculoskeletal complaints, somatic complaints, medical diagnoses and anxiety and depression) measured before the accident were associated with development of chronic whiplash. Study two investigated whether socio-demographic and health-related variables measured in individuals with whiplash were associated with recovery. Study three used prospective data from Denmark, following individuals with acute whiplash for a year. Coping and health care preferences reported during the first few days following the whiplash accident were described. The associations between early health care/coping preferences and outcome (neck pain/reduced capability to work) one year later were investigated. Results: The three studies in this thesis show that: Poor pre-injury health, both mental and somatic, is associated with development of chronic whiplash (study one). Similar health complaints reported among individuals with whiplash are associated with nonrecovery from the condition (study two). A high use of health care services and medications before the injury is associated with increased risk of developing chronic whiplash (study one). High use of health care and medications among individuals with whiplash is associated with non-recovery (study two). Patients’ coping preferences in the acute phase after whiplash injuries are associated with outcome in whiplash (study three): Reporting passive coping preferences and need of health care increase the risk of neck pain and reduced capability to work one year later. Individuals who prefer active coping and want to keep living as normal have a better prognosis. Conclusion: Chronic whiplash is a complex condition characterized by a broad range of complaints. Clinical imaging and accident related factors seem to be poor predictors of outcome. Poor pre-injury health and use of health services and medications are associated with subsequent chronic whiplash. Similar variables in individuals with whiplash are associated with non-recovery. Preferring use of health care and passive coping after whiplash is associated with non-recovery. As such chronic whiplash resembles functional somatic syndromes. Knowledge of prognostic factors might aid identification of individuals at risk of an adverse prognosis after whiplash, enabling earlier treatment for those most in need. However, health care in whiplash is often ineffective and might itself increase the risk of poor recovery. More research on treatment of whiplash is needed; in particular on whether targeting prognostic factors like those identified in this thesis can improve recovery

Long Waiting Times for Elective Hospital Care – Breaking the Vicious Circle by Abandoning Prioritisation

Background: Policies assigning low-priority patients treatment delays for care, in order to make room for patients of higher priority arriving later, are common in secondary healthcare services today. Alternatively, each new patient could be granted the first available appointment. We aimed to investigate whether prioritisation can be part of the reason why waiting times for care are often long, and to describe how departments can improve their waiting situation by changing away from prioritisation. Methods: We used patient flow data from 2015 at the Department of Otorhinolaryngology, Haukeland University Hospital, Norway. In Dynaplan Smia, Dynaplan AS, dynamic simulations were used to compare how waiting time, size and shape of the waiting list, and capacity utilisation developed with and without prioritisation. Simulations were started from the actual waiting list at the beginning of 2015, and from an empty waiting list (simulating a new department with no initial patient backlog).Results: From an empty waiting list and with capacity equal to demand, waiting times were built 7 times longer when prioritising than when not. Prioritisation also led to poor resource utilisation and short-lived effects of extra capacity. Departments where prioritisation is causing long waits can improve their situation by temporarily bringing capacity above demand and introducing “first come, first served” instead of prioritisation. Conclusion: A poor appointment allocation policy can build long waiting times, even when capacity is sufficient to meet demand. By bringing waiting times down and going away from prioritisation, the waiting list size and average waiting times at the studied department could be maintained almost 90% below the current level – without requiring permanent change in the capacity/demand ratio

What accuracy statistics really measure

Provides the software estimation research community with a better understanding of the meaning of, and relationship between, two statistics that are often used to assess the accuracy of predictive models: the mean magnitude relative error (MMRE) and the number of predictions within 25% of the actual, pred(25). It is demonstrated that MMRE and pred(25) are, respectively, measures of the spread and the kurtosis of the variable z, where z=estimate/actual. Thus, z is considered to be a measure of accuracy, and statistics such as MMRE and pred(25) to be measures of properties of the distribution of z. It is suggested that measures of the central location and skewness of z, as well as measures of spread and kurtosis, are necessary. Furthermore, since the distribution of z is non-normal, non-parametric measures of these properties may be needed. For this reason, box-plots of z are useful alternatives to simple summary metrics. It is also noted that the simple residuals are better behaved than the z variable, and could also be used as the basis for comparing prediction system

The effect of mindfulness training on employees in a dynamic organizational setting

The access to information and multiple sources of communication has changed the way we work, and relate to our work day. The boundaries between work and home often disappear, increasing potentially employees’ stress level, diminish-ing cognitive capabilities, and splitting attention between numerous tasks. The consequences of multitasking have been widely studied, as well as individual differences. Based on other studies, mindfulness based stress reduction (MSBR) method appears to have a positive effect e.g. on attention, working memory, stress and empathy. Thus, this experiment introduces an intervention in the form of mindfulness training, which lasted for 12 weeks for all 110 employees, who are located in 13 countries world wide. In addition, employees attended a seminar per week during 10 weeks. These seminars were mainly based on positive psychology. In order to collect data three surveys were sent out (before the intervention, 12 weeks after the first seminar and 6 months later). Two specific measurements were used, which are Mind-fulness Awareness Scale (MASS) and Perceived Stress Scale (PSS). Findings showed a significant increase in MAAS, and diminishing values in PSS, meaning that treatment, in the form of MBSR had an affect on the perceived stress in the firm

Democracy and the Discourse on Relevance Within the Academic Profession at Makerere University

Democracy and the Discourse of Relevance is set against the backdrop of the spread of neoliberal ideas and reforms since the 1980s, accepting also that these ideas are rooted in a longer history. It focuses on how neoliberalism has worked to transform the university sector and the academic profession. In particular, it examines how understandings of, and control over, what constitutes relevant knowledge have changed. Taken as a whole, these changes have sought to reorient universities and academics towards economic development in various ways. This includes the installation of strategies for how institutions and academics achieve recognition and status within the academy, the privatisation of educational services and the downgrading of the value of public higher education, as well as a steady shift away from the public funding for universities. Research universities are increasingly adopting a user- and market-oriented model, with an emphasis on meeting corporate demands, the privileging of short-term research, and a strong tendency to view utility, and the potential to sell intellectual property for profit, as primary criteria for determining the relevance of academic knowledge. The privatisation of education services and the reorienting of universities towards the needs of the ‘knowledge economy’ have largely succeeded in transforming the discourse around the role of the academic profession in society, including in many African countries. Makerere University in Uganda has often been lauded as an example of successful transformation along neoliberal lines. However, our research into the working lives of academics at Makerere revealed a very different picture. Far from epitomising the allegedly positive outcomes of neoliberal reform, academics and postgraduate students interviewed at Makerere provide worrying insights into the undermining of a vibrant and independent academic culture. The stories of the ordinary academics on the ground, the empirical focus of the book, are in contrast to the claimed successes of the university; and the official stories of the university leadership and administration paint a picture of an academic profession in crisis. With diminishing influence on deciding what is relevant knowledge and thus on processes of democratization of their own institution and society, academic freedom is also losing its value. This perspective from the ground-level exposes the many problems that neoliberal reforms have created for academics at Makerere, leaving them feeling disempowered, often reducing them to the status of consultants. We also show how a range of local initiatives ­are steadily increasing resistance to the neoliberal model. We consider how academics and others can further mobilise to regain control over what knowledge is considered relevant, and thereby deepen democracy. In so doing, we aim to highlight some responses and actions that have proven effective so far. Democracy and the Discourse of Relevance will hopefully help to change the systems that value knowledge in ways that are driving research institutions towards competitive and market-like behaviour. We also aim to contribute to contemporary debates about what knowledge is relevant

Interaction of three-dimensional acoustic beam with fluid-loaded solid plate: Axial near- to far-field transmission at normal beam incidence

Axial radiation from leaky Lamb waves propagating in a 6.05 mm water-immersed steel plate being excited by a sound beam normally incident to the plate, is investigated as a function of axial distance, z, and frequency, f, over the 350–1000 kHz frequency band of the S2, A2, and A3 Lamb modes in the plate. For certain leaky Lamb modes, prior literature has revealed complex characteristics in the transmitted pressure field close to the plate, caused by diffraction due to the finite angular spectrum of the incident beam. The present work extends earlier work by bringing insight into the changes of these field characteristics in the near- and far-field of the transmitted beam, over the frequency band of leaky Lamb modes, for normal beam incidence to the plate. A baffled piston source in a full-wave angular spectrum propagation model is used to analyze the phenomena involved. Maxima and minima that can not be described with plane wave theory are observed in the frequency spectrum of the axial pressure transfer function through the plate. At very long ranges the normalized transmitted sound beam tends to attain characteristics of the plate’s plane-wave transmission coefficient, for two of the leaky Lamb modes. Nearfield interference phenomena not described in prior literature are identified. For the leaky Lamb mode associated with a backward-wave branch close to the fundamental thickness-extensional resonance in the plate, TE1, the axial near-field is shown to extend to very far ranges. Supplementary measurements add confidence to the simulation results and findings. Besides of their fundamental significance in the study and understanding of sound beams transmitted through a fluid-immersed solid plate, the results are of importance e.g. in immersion applications where material characterization is made using fluid-coupled ultrasonic transducers in a through-thickness resonant transmission setup, such as plate thickness or material properties measurements.publishedVersio