Magister Scientiae - MSc (Statistics and Population Studies)

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An application of factor analysis on a 24-item scale on the attitudes towards AIDS precautions using Pearson, Spearman and Polychoric correlation matrices
(University of the Western Cape, 2006) Abdalmajid, Mohammed Babekir Elmalik; Blignaut, Renette; Dept. of Statistics; Faculty of Science
The 24-item scale has been used extensively to assess the attitudes towards AIDS precautions. This study investigated the usefulness and validity of the instrument in a South African setting, fourteen years after the development of the instrument. If a new structure could be found statistically, the HIV/AIDS prevention strategies could be more effective in aiding campaigns to change attitudes and sexual behaviour.
Assessing the high-risk behaviour of first year students entering the University of the Western Cape
(University of the Western Cape, 2007) Abels, Melissa Dione; Blignaut, Renette; Doctor, V; Dept. of Statistics; Faculty of Science
The motivation of this study is to assess the high risk behaviors that contribute to the spread of HIV and AIDS among the youth. The most influential high risk behaviours that contribute to the spread of HIV and AIDS are unprotected sexual intercourse and having more than one sexual partner.The population for this study includes all full time first year students who registered for the first time in 2006 that attended the orientation week. A stratified, sequential random sample was drawn from the students attending the orientation.
Fitting extreme value distributions to the Zambezi river flood water levels recorded at Katima Mulilo in Namibia
(University of the Western Cape, 2005) Kamwi, Innocent Silibelo; Koen, C; Blignaut, Renette; Dept. of Statistics; Faculty of Science
The aim of this research project was to estimate parameters for the distribution of annual maximum flood levels for the Zambezi River at Katima Mulilo. The estimation of parameters was done by using the maximum likelihood method. The study aimed to explore data of the Zambezi's annual maximum flood heights at Katima Mulilo by means of fitting the Gumbel, Weibull and the generalized extreme value distributions and evaluated their goodness of fit.
Perceived quality and utilisation of maternal health services in peri-urban, commercial farming, and rural areas in South Africa
(University of the Western Cape, 2006) Matizirofa, Lyness; Jackson, D; Blignaut, Renette; Dept. of Statistics; Faculty of Science
This investigation aimed to determine factors that influence women's utilisation of maternal health services, with specific focus on the quality of care and services available to disadvantaged communities in South Africa. It used the women's perspectives to assess the quality of maternal healthcare services in peri-urban commercial farming and rural areas with the purpose of understanding why women utilise maternal services the way they do.
Quantified assessment to enhance student learning in the sciences at UWC
(University of the Western Cape, 2005) Lombard, Ronell; Blignaut, Renette; Dept. of Biotechnology; Faculty of Science
This project discusses whether the British prototype questionnaire called the Assessment Experience Questionnaire (AEQ) could be standardized as a quantifier of assessment and be used at a multicultural institute such as the University of the Western Cape (UWC). This questionnaire was created in the United Kingdom to assist lecturers in evaluating and developing their assessment systems.
The statistical theory underlying human genetic linkage analysis based on quantitative data from extended families
(University of the Western Cape, 2010) Galal, Ushma; van der Merwe, Lize; Blignaut, Renette; Dept. of Statistics; Faculty of Science
Traditionally in human genetic linkage analysis, extended families were only used in the analysis of dichotomous traits, such as Disease/No Disease. For quantitative traits, analyses initially focused on data from family trios (for example, mother, father, and child) or sib-pairs. Recently however, there have been two very important developments in genetics: It became clear that if the disease status of several generations of a family is known and their genetic information is obtained, researchers can pinpoint which pieces of genetic material are linked to the disease or trait. It also became evident that if a trait is quantitative (numerical), as blood pressure or viral loads are, rather than dichotomous, one has much more power for the same sample size. This led to the development of statistical mixed models which could incorporate all the features of the data, including the degree of relationship between each pair of family members. This is necessary because a parent-child pair definitely shares half their genetic material, whereas a pair of cousins share, on average, only an eighth. The statistical methods involved here have however been developed by geneticists, for their specific studies, so there does not seem to be a unified and general description of the theory underlying the methods. The aim of this dissertation is to explain in a unified and statistically comprehensive manner, the theory involved in the analysis of quantitative trait genetic data from extended families. The focus is on linkage analysis: what it is and what it aims to do. There is a step-by-step build up to it, starting with an introduction to genetic epidemiology. This includes an explanation of the relevant genetic terminology. There is also an application section where an appropriate human genetic family dataset is analysed, illustrating the methods explained in the theory sections.
Stigmatization of and discrimination against people who are HIV positive, or have AIDS – a female perspective in Zwartwater, Eastern Cape Province
(University of the Western Cape, 2011) Malgas, Khangela Frida; Blignaut, Renette
The aim of this study is to investigate the perceived stigmatization of and discrimination against people who are HIV positive or people who are living with AIDS. One questionnaire was used to collect qualitative and quantitative data. Data collection was conducted for a period of three weeks in the Eastern Cape province at the Zwartwater area in Lady Frere and at the Queenstown (Frontier) Hospital. A sample of 170 (of the 900) females was interviewed, of which 100 were sequentially sampled from the community and 70 were sequentially sampled whilst they were queuing at the Queenstown (Frontier) Hospital for care. Households from the rural area were selected by visiting every fourth house on the route linking the houses in this area. At the hospital, selection started at the back of the queue and every sixth person was selected and interviewed. Scores were calculated for knowledge and attitudes towards people who are HIV positive and towards people who have AIDS. It was found that knowledge and attitude scores did not differ between the various age groups tested. It was furthermore found that an increased knowledge score improved attitudes towards people who are HIV-positive or have AIDS.
Teaching logarithmic inequalities using omnigraph
(University of the Western Cape, 2007) Basadien, Soraya.; Blignaut, Renette; Dept. of Statistics; Faculty of Science
Over the last few years it became clear that the students struggle with the basic concepts of logarithms and inequalities, let alone logarithmic inequalities due to the lack of exposure of these concepts at high school. In order to fully comprehend logarithmic inequalities, a good understanding of the logarithmic graph is important. Thus, the opportunity was seen to change the method of instruction by introducing the graphical method to solve logarithmic inequalities. It was decided to use an mathematical software program, Omnigraph, in this research.
Throughput of UWC students who did at least one semester of third-year statistics
(University of the Western Cape, 2005) Latief, Abduraghiem; Blignaut, Renette; Kotze, D; Dept. of Statistics; Faculty of Science
This study explored the completion rates (the number of years a student takes to complete a degree) of graduates at the University of the Western Cape. Differences between students who finished their studies in the prescribed time of three years and those who took longer than the prescribed time was highlighted.
Using a weighted bootstrap approach to identify risk factors associated with the sexual activity of entering first-year students at UWC
(2013) Brydon, Humphrey; Blignaut, Renette
This thesis looks at the effect that the introduction of various techniques (weighting, bootstrapping and variable selection) has on the accuracy of the modelling process when using logistic regression. The data used in the modelling process is based on the sexual activity of entering first-year students at the University of the Western Cape, therefore, by constructing logistic regression models based on this data, certain predictor variables or factors associated with the sexual activity of these students are identified. The sample weighting technique utilized in this thesis assigned a weight to a student based on gender and racial representations within a sample when compared to the population of the entering first-year. The use of a sample weighting technique is shown to produce a more effective modelling process than a modelling process without weighting. The bootstrapping procedure is shown to produce logistic regression models that are more accurate. Utilizing more than 200 bootstrap samples did not necessarily produce logistic regression models that were more accurate than using a total of 200 bootstrap samples. It is, however, concluded that a weighted bootstrap modelling procedure will result in more accurate models compared to a procedure without this intervention. The forward, backward, stepwise, Newton-Raphson and Fisher variable selection methods are used. The Newton-Raphson and Fisher methods are found not to be effective when used in a logistic modelling process, whereas the forward, backward and stepwise methods are all shown to produce very similar results. Six predictor variables or factors are identified with respect to the sexual activity of the specified students: the age of the student; whether they consume alcohol or not; their racial grouping; whether an HIV test has been taken; the importance of religion in influencing their sexual behaviour; and whether they smoke or not.i i Conclusions are reached with respect to improvements that could be made to the HIV prevention programme at UWC with reference to the sexual activity of entering first-years.
Using factor analysis to determine why students select UWC as higher education institute
(University of the Western Cape, 2009) Osman, Abuelgasim Ahemd Atta-Almanan; Blignaut, Renette; NULL; Faculty of Science
This study investigates the most important reasons behind the rst-year students' decision to select University of the Western Cape (UWC) as higher education institution. These reasons were organized into a few factors for easy interpretation. The data to be analyzed for this project is a subsection of the data collected during the orientation period of 2008. During the orientation week of 2008, the questionnaires were completed on a voluntary basis by new rst-year students. All questionnaires were anonymously completed and therefore the data does not contain any information that could be linked to any individual. For the purpose of this study, only the black African and coloured students were considered. The other racial groups were not analyzed due to too small sample sizes. Questionnaires with missing information on the reasons for selecting UWC were not nalyzed. We ended up with a sample of size 600. The data were statistically analyzed, using descriptive statistics, bivariate analyses, factor analysis, coefficient of congruence and bootstrap factor analysis. The results indicated that the most important reasons a ecting students to choose UWC were identi ed as good academic reputation, family member's advice, UWC graduates are successful and UWC graduates get good jobs. The least important reasons were found to be not accepted anywhere, parents / family members graduated from UWC, recruited by UWC and wanted to study near to home. The results also indicated that there were significant differences among students according to population groups, parent's monthly income and grade 12 average. Factor analysis of 12 variables yielded three extracted factors upon which student decisions were based. Similarities of these three factors were tested, and a high similarity among demographic characteristics and grade 12 average were found. Additional analyses were conducted to measure the accuracy of factor analyses models constructed using Spearman and Polychoric correlation matrices. The results indicated that both correlation matrices were nbiased, with higher variance and higher loadings when the Polychoric correlation matrix was used to construct a factor analysis model for categorical data.
Waiting to die: staging of HIV positive people at the first HIV test - Region A, Nelson Mandela Metropole (January 1991-April 2000)
(University of the Western Cape, 2006) Cupido, Ynoma; Stiegler, Nancy; Blignaut, Renette; Dept. of Statistics; Faculty of Science
This project suggested that HIV people in Region A (Nelson Mandela Metropole, formerly Port Elizabeth) health district of the Eastern Cape, seek HIV testing when they are already in stages three (late disease) and four (AIDS) of HIV infection. Data had been obtained from the AIDS Training Information and Counselling Centre in the Nelson Mandela Metropole in 2000. The consequences of diagnoses only in the advanced stages of HIV infection will have a devastating impact on case management. Therefore, this paper yielded important data for South African policy makers to write health and welfare policies that might improve the quality of life of those terminally infected with HIV.

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