Recent Submissions

  • Application of the moving block bootstrap method to resampled efficiency : the impact of the choice of block size 

    Retief, Jan (Stellenbosch : Stellenbosch University, 2021-12)
    ENGLISH SUMMARY : Modern Portfolio theory was first developed in the 1950’s and revolutionised the way in which financial information is used to construct portfolios. Unfortunately, the theory is limited by the sensitivity ...
  • On the convergence of gaussian belief propagation with nodes of arbitrary size 

    Kamper, Francois; Steel, Sarel J.; Du Preez, Johan A. (Journal of Machine Learning Research, 2019)
    This paper is concerned with a multivariate extension of Gaussian message passing applied to pairwise Markov graphs (MGs). Gaussian message passing applied to pairwise MGs is often labeled Gaussian belief propagation (GaBP) ...
  • Improving collaborative filtering with fuzzy clustering 

    Beukman, Erika (Stellenbosch : Stellenbosch University, 2021-12)
    ENGLISH SUMMARY : Recommender systems are machine learning algorithms widely used across various industries to predict user preference for sets of items in order to recommend items to the user. Since it narrows down the ...
  • Longitudinal population dynamics of staphylococcus aureus in the nasopharynx during the first year of life 

    Abdulgader, Shima M.; Robberts, Lourens; Ramjith, Jordache; Nduru, Polite M.; Dube, Felix; Lubbe, Sugnet, 1973-; Zar, Heather J.; Nicol, Mark P. (Frontiers Media, 2019)
    Background: Staphylococcus aureus colonization is a risk factor for invasive disease. Few studies have used strain genotype data to study S. aureus acquisition and carriage patterns. We investigated S. aureus nasopharyngeal ...
  • Basic in-mouth attribute evaluation : a comparison of two panels 

    Mihnea, Mihaela; Aleixandre-Tudo, Jose Luis; Kidd, Martin; Du Toit, Wessel (MDPI, 2018-12-21)
    Astringency is often difficult to evaluate accurately in wine because of its complexity. This accuracy can improve through training sessions, but it can be time-consuming and expensive. A way to reduce these costs can be ...
  • PPCI : an R package for cluster identification using projection pursuit 

    Hofmeyr, David P.; Pavlidis, Nicos G. (Projection pursuit (Statistics) -- Methods, 2019-12)
    This paper presents the R package PPCI which implements three recently proposed projection pursuit methods for clustering. The methods are unified by the approach of defining an optimal hyperplane to separate clusters, and ...
  • Influence of socio-economic and psychosocial profiles on the human breast milk bacteriome of South African women 

    Ojo-Okunola, Anna; Claassen-Weitz, Shantelle; Mwaikono, Kilaza S.; Lubbe, Sugnet, 1973-; Stein, Dan J.; Zar, Heather J.; Nicol, Mark P.; Du Toit, Elloise (MDPI, 2019-06-20)
    The human breast milk (HBM) bacteriome is an important, continuous source of microbes to the neonate in early life, playing an important role in shaping the infant’s intestinal bacteriome. Study of the composition of the ...
  • Levy processes and quantum mechanics : an investigation into the distribution of log returns 

    Le Roux, Christiaan Hugo (Stellenbosch : Stellenbosch University, 2021-03)
    ENGLISH SUMMARY : It is well known that log returns on stocks do not follow a normal distribution as is assumed under the Black-Scholes pricing formula. This study investigates alternatives to Brownian Motion which are ...
  • Validation of independent components using a hypothesis testing approach 

    De Koker, Corine (Stellenbosch : Stellenbosch University, 2020-12)
    ENGLISH ABSTRACT: The main focus of this thesis is the validation of Independent Component Analysis (ICA), a popular technique used in signal processing. In a typical application, the purpose of ICA is to extract non-Gaussian ...
  • Feature selection for multi-label classification 

    Contardo-Berning, Ivona E. (Stellenbosch : Stellenbosch University, 2020-12)
    ENGLISH ABSTRACT : The field of multi-label learning is a popular new research focus. In the multi-label setting, a data instance can be associated simultaneously with a set of labels instead of only a single label. This ...
  • The appropriateness of ISDA SIMM for delta risk initial margin calculations in the South African over-the-counter interest rate swap market 

    Cronje, Robert (Stellenbosch : Stellenbosch University, 2020-12)
    ENGLISH SUMMARY : This research assignment assesses the appropriateness of the calibrations in the ISDA SIMM for calculating delta risk initial margin (IM) in the current over-the-counter interest rate swap market in South ...
  • Bayesian machine learning : theory and applications 

    Payne, Megan Wendy (Stellenbosch : Stellenbosch University, 2020-12)
    ENGLISH SUMMARY : Machine learning problems in general are concerned with the ability of different methods and algorithms to extract useful and interpretable information from large datasets, possibly ones which are corrupt ...
  • A deep convolutional neural network architecture for image classification 

    Pretorius, Willem Lodewikus (Stellenbosch : Stellenbosch University, 2020-12)
    ENGLISH SUMMARY : Convolutional Neural Networks (CNNs), a specialised form of Neural Networks (NNs), are wellknown for their state-of-the-art results obtained in Computer Vision (CV) and Deep Learning (DL) tasks throughout ...
  • Categorical CVA biplots 

    Rodwell, David Timothy (Stellenbosch : Stellenbosch University, 2020-12)
    ENGLISH ABSTRACT: In the modern era a great amount of emphasis is placed on data visualisation, especially in cases where a large amount of data is present. Usually, in these instances, the data is of a high-dimensional ...
  • Exploding biplots with density axes in Plotly 

    Sandilands, Delia (Stellenbosch : Stellenbosch University, 2020-12)
    ENGLISH SUMMARY : Biplots are visual approximations to multidimensional data sets and are very useful in data driven procedures. However, certain issues occur when dealing with a large number of observations or variables. ...
  • Optimizing 16S rRNA gene profile analysis from low biomass nasopharyngeal and induced sputum specimens 

    Claassen-Weitz, Shantelle; Gardner-Lubbe, Sugnet; Mwaikono, Kilaza S.; Du Toit, Elloise; Zar, Heather J.; Nicol, Mark P. (BMC (part of Springer Nature), 2020-05-12)
    Background: Careful consideration of experimental artefacts is required in order to successfully apply highthroughput 16S ribosomal ribonucleic acid (rRNA) gene sequencing technology. Here we introduce experimental design, ...
  • HIV-exposure, early life feeding practices and delivery mode impacts on faecal bacterial profiles in a South African birth cohort 

    Claassen-Weitz, Shantelle; Gardner-Lubbe, Sugnet; Nicol, Paul; Botha, Gerrit; Mounaud, Stephanie; Shankar, Jyoti; Nierman, William C.; Mulder, Nicola; Budree, Shrish; Zar, Heather J.; Nicol, Mark P.; Kaba, Mamadou (Nature Research, 2018)
    There are limited data on meconium and faecal bacterial profiles from African infants and their mothers. We characterized faecal bacterial communities of infants and mothers participating in a South African birth cohort. ...
  • Credit curve estimation and corporate bonds in the South African market 

    Clift, Peter-John (Stellenbosch : Stellenbosch University, 2020-03)
    ENGLISH SUMMARY : Accurate fair value measurement of financial instruments serves as one of many mechanisms to enhance the integrity of financial institutions, particularly as it relates to counterparty credit risk. In ...
  • Estimating expected exposure profiles using biplot interpolation 

    Van Niekerk, Francesca (Stellenbosch : Stellenbosch University, 2020-03)
    ENGLISH SUMMARY : The accounting standards provides guidelines on how to determine the fair value for a financial asset or liability held at fair value. When considering the fair value of derivative instruments, some additional ...
  • Strategies for combining tree-based learners 

    Meyer, Nicholas George (Stellenbosch : Stellenbosch University., 2020-04)
    ENGLISH ABSTRACT: In supervised statistical learning, an ensemble is a predictive model that is the conglomeration of several other predictive models. Ensembles are applicable to both classification and regression problems ...

View more