Magister Scientiae - MSc (Statistics and Population Studies)

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https://hdl.handle.net/10566/14875

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Browsing by Author "Brydon, Humphrey"

Now showing 1 - 4 of 4
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    A clustering smart phone users based on the digimiter survey and mobile application data
    (University of the Western Cape, 2023) Kuse, Buhle; Brydon, Humphrey
    Digimiter Survey
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    Development of a challenger price sensitivity model to improve Santam's new business optimisation framework
    (University of the Western Cape, 2021) Engelke, Nina; Brydon, Humphrey
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    Modelling risk factors related to the performance of two oceans half marathon runners between 2012 and 2015
    (University of the Western Cape, 2022) Jordaan, Marlise; Brydon, Humphrey
    Limited literature is available on the effect of factors associated with the improvement in performance of Two Oceans Half Marathon (TOHM) runners. This study examined factors associated with the improvement in performance of a runner over a 4-year period for the Two Oceans Half Marathon through the application of a linear mixed model. A subset of data was identified that according to the literature had an impact on the performance of a half marathon runner. Univariate analysis was conducted to identify factors that had an impact on the performance of the runners and a linear mixed model was applied to the model adjusted for age, gender and body mass index (BMI) containing interaction effects to determine the extent to which these factors influence the change in performance of the runners.
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    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.