Master of Science / Department of Statistics / Weixing Song / There has been a continuing interest among statisticians in the problem of regression models wherein the independent variables are measured with error and there is considerable literature on the subject. In the following report, we discuss the errors-in-variables regression model: yi = β0 + β1xi + β2zi + ϵi,Xi = xi + ui,Zi = zi + vi with i.i.d. errors (ϵi, ui, vi), for i = 1, 2, ..., n and find the least square estimators for the parameters of interest. Both weak and strong consistency for the least square estimators βˆ0, βˆ1, and βˆ2 of the unknown parameters β0, β1, and β2 are obtained. Moreover, under regularity conditions, the asymptotic normalities of the estimators are reported.

Student Number : 0003555T - MSc (Eng) dissertation - School of Electrical and Information Engineering - Faculty of Engineering and the Built Environment / Successful radiotherapy treatments with high-energy proton beams require the accurate positioning of patients. This paper investigates computational methods for achieving accurate treatment setups in proton therapy based on the geometrical differences between a double exposed portal radiograph (PR) and a reference image obtained from the treatment planning process. The first step in these methods involves aligning the boundary of the radiation field in the PR with a reference boundary defined by the treatment plan. We propose using the generalised Hough transform (GHT), followed by an optimisation routine to align the field boundaries. It is found that this method worked successfully on ten tested examples, and aligns up to 82% of reference boundary points onto the field boundary. The next step requires quantising the patients anatomical shifts relative to the field boundary. Using simulated images, a number of intensity-based similarity measures and optimisation routines are tested on a 3D/2D registration. It is found that the simulated annealing algorithm minimising the correlation coefficient provided the most accurate solution in the least number of function evaluations.

faculty of Humanities School of Human and Community Development 9807986h IsrealN@umthombo.wits.ac.za / The issue of bias, whether a psychological test measures what it claims to measure similarly across different groups, remains a fundamental concern within the field of psychometrics, particularly within South Africa, where a history riddled with oppression, discrimination and malpractice in the area has led to suspicion, mistrust and legislation banning the use of many psychological tests as invalid and unfair (Foxcroft & Roodt, 2001; Murphy & Davidshofer, 2001; Nell, 1999). There is thus clearly a need for additional and more detailed investigations of the way specific individual tests function in the South African context. This study attempted to creatively examine systematic differences in performance on one specific test, the Raven’s Advanced Progressive Matrices (RAPM), on the basis of home language and gender, factors seldom investigated in the literature. A sample of one hundred Psychology first-year students completed a demographic questionnaire, the RAPM, the Similarities sub-test of the South African Wechsler Adult Intelligence Scales (SAWAIS) and an adapted version of the Reading Comprehension subtest of the Stanford Diagnostic Reading Test (SDRT). The data gathered was then utilized to explore four main research questions. Firstly, in order to establish construct comparability, the relationship between the RAPM and a more verbally-oriented measure of g, the Similarities sub-test of the SAWAIS, was assessed. Results indicated a relatively strong positive relationship between the two measures (r = 0.66), and no significant differences between the correlations on the basis of either gender or home language. Secondly, in order to explore the relationship between the RAPM and English comprehension, the study assessed the relationship between overall, literal and inferential scores on an adapted version of the Reading Comprehension sub-test of the SDRT and the RAPM. Results indicated only a moderate relationship between the two tests (r = 0.65), no difference in the relationship between RAPM performance and literal comprehension or inferential comprehension, and no difference in the relationship between the two tests on the basis of either gender or home language. Thirdly, in order to establish whether items were found to be difficult in a similar way across the different gender and home language groups, p-values and regression lines were calculated. These indicated that significant differences in level of item difficulty were experienced between English and African language speakers, although no differences were apparent in item difficulty on the basis of gender. 5 Lastly, in order to establish whether qualitative differences in performance on the basis of ability (as estimated by performance on the RAPM), gender or language existed, a discrimination analysis examining the types of errors made by each group was performed. Repeated measures ANOVAs and multiple comparison post-hoc analyses revealed significant differences in the types of errors made on the basis of ability and home language, but not gender. The post-hoc analyses suggested that those of higher ability or first language English speakers were more likely to make incomplete correlate errors, while those of lower ability or speaking African first languages were more likely to make confluence of ideas errors. In general, the findings of the study seemed to suggest that the RAPM, while not biased on the basis of gender, might contain a deep-seated language bias despite their non-verbal presentation.

Magister Educationis - MEd / Every year there is a national outcry by educationists in South Africa relating to the poor performance of grade 12 mathematics learners. This is an unsatisfactory state of affairs in a country where mathematics is seen as playing a pivotal role in the preparation of students in disciplines for careers in science and technology. Interventions by the Department of Basic Education as well as by provincial education departments do not seem to be successful in stemming the tide in the decline of standards in the mathematical performance of learners. It is this which has motivated this study.The aim of this study was to identify the types of errors committed by students in their responses to question one of Paper 1 in the final Grade 12 mathematics examinations of 2010. By reviewing the work done by different authors, an analytical framework was compiled that was used to identify and to label errors in the written responses of learners. This study has adopted a documentary analysis approach and has selected a representative sample of examination scripts of Western Cape students who wrote the first paper of the grade 12 mathematics examination in 2010. The result shows that during the analysis of 1959 scripts (the sample taken from different educational departments and districts), 4163 errors were identified. These errors have been identified based on the above-mentioned analytical framework. Comparisons were labeled according to the different types of errors, across the different ex- department schools and per districts. If the percentage is calculated based on the number of scripts analyzed, the number of errors varies from 12% careless errors to 40% calculation errors. It was also noticed that the number of errors found in the urban districts was higher than all of the errors found in the different rural districts. In return, in the urban districts, the numbers of errors found were evenly distributed over the four districts. When the different ex-department schools were compared, the numbers of application and procedural errors were significantly higher in the DET schools(Department of Education and Training, which consists of mostly black disadvantaged learners) than all the other schools. The rest of the errors were evenly distributed over all the exdepartment schools. The inability of learners solving inequality equations stood out as a major concern.

This thesis examines the joint impact of earnings management incentives (i.e., income smoothing, solvency management and tax management) and reinsurance, together with other institutional factors, on the magnitude and direction of claim (loss) reserves errors in the UK’s property-liability insurance industry. Two reserve error definitions, found in literature, are employed to conduct the analysis. Furthermore, a panel data generalised methods of moments (GMM) estimator is employed to incorporate the dynamic nature of current and past loss reserving errors. Using the GMM estimator in a panel of 151 firms over a period from 1991 and 2005, the study finds support for the conclusions of some prior studies but also inconsistencies with other previous research. The present study finds that the inferences drawn from empirical analyses can be influenced by the definition of loss reserving errors and to some extent how other incentive variables are defined. The results of this study suggest that discretionary loss reserving behaviour tends to persist from one year to another. Therefore, ignoring the dynamic nature of loss reserving errors could lead to biased and unreliable conclusions. The empirical results of this study also find that property-liability insurance managers manipulate claims reserves in order to smooth company’s earnings across accounting periods. Furthermore, empirical evidence is found which indicates that high levels of reinsurance ceded help to reduce the incidence of error in loss reserves. Contrary to expectations, the evidence presented in this thesis suggests that highly solvent insurers under-estimate their claims liabilities. However, no empirical support is found to indicate that insurers over-reserve in order to reduce and/or postpone period tax liabilities. The study also produced mixed results regarding the relation between the type of reinsurance cover used and claim reserve errors. Nevertheless, the empirical results show that firm-specific effects, such as company size and product mix, can have effect on the accuracy of insurers’ reserves. Finally, as this study gives an important insight on discretionary loss reserve manipulation, its conclusions could be of interest and relevance to the business decisions of investors, policyholders, regulators, and other interested parties (e.g., credit rating agencies and accounting standard settlers).

Medication errors are a global concern that may affect patients' hospital stays, patients' lives after discharge, treatment costs, and mortality rates. Understanding medication errors among nursing students may help in preventing these errors as nurses are responsible for safe medication administration. The purpose of this descriptive phenomenological study was to examine upper-level nursing students' understanding of and experiences with medication administration and patient safety. Benner's nursing theory of novice to expert and Dreyfus's model of skill acquisition comprised the conceptual framework. Research questions focused on students' perceptions of safe medication administration. Face-to-face interviews were conducted with 7 upper-level nursing students from a baccalaureate nursing program in the Southeastern U.S. utilizing convenience sampling. Colaizzi's analysis strategy was followed in determining themes and clustering data into categories. Three major themes emerged from the data that included learning curve referring to the rigor of the pharmacology course, gaining self-confidence, and reliance on preceptor. Two sub-themes were identified from the theme learning curve, which included fear of making a mistake causing harm to a patient, and appreciating the complexity of the working environment and the intricacy of the patients. Using study findings, a hybrid pharmacology and medication administration course for nursing students was developed. The course may improve nursing students' confidence in their skills and knowledge and enable them to provide a safer environment for patients. Implications for positive social change include a potential reduction in medication errors and related adverse outcomes experienced by patients and their families and by health care organization.

The high resolution silicon Pixel detector is critical in event vertex reconstruction and in particle track reconstruction in the ATLAS detector. During the pixel data taking operation, some modules (Silicon Pixel sensor +Front End Chip+ Module Control Chip (MCC)) go to an auto-disable state, where the Modules don't send the data for storage. Modules become operational again after reconfiguration. The source of the problem is not fully understood. One possible source of the problem is traced to the occurrence of single event upset (SEU) in the MCC. Such a module goes to either a Timeout or Busy state. This report is the study of different types and rates of errors occurring in the Pixel data taking operation. Also, the study includes the error rate dependency on Pixel detector geometry.

No description available.

No description available.

No description available.