Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 7 of 7 for “"compositional data analysis"”.
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Improving the efficiency of modelling complex physical activity data using longitudinal compositional data analysis
Physical activity (PA) data are often objectively collected using an accelerometer worn by the participant, with data collected over a pre-specified period. PA has historically been summarised as a single numerical measure, often the number of minutes spent in moderate-to-vigorous PA, disregarding …
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PERFORMANCE OF THE TWO SAMPLE LIKELIHOOD RATIO TEST UNDER A NESTED DIRICHLET: A SIMULATION STUDY
<p>Compositional data analysis (CoDA) addresses multivariate data constrained to a constant sum, such as proportions or percentages. Originating from early warnings regarding misinterpretation by Pearson (1897), the field was formalized by John Aitchison in 1986, whose foundational work remains …
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Virtually Alone: Exploring the Effects of Technology and Job Design on Loneliness in Remote Work Arrangements
… to workplace loneliness. To complement this, data was also collected on which information communication technology (ICT) employees use most often. A total of 305 employees from the three work models were surveyed. The results showed that as virtuality of the work arrangement increased so did …
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Compositional Associations of Time Spent in Sleep, Screen Time, and Physical Activity with Polysubstance Use in Adolescents
… products, alcohol, cannabis, and illicit drugs. Compositional data analysis was used to investigate relationships between the movement behavior composition and its components with high polysubstance use. Compositional isotemporal substitutions estimated how relocating time from one movement …
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Geochemical and Microbial Controls of Groundwater Quality in Northwestern Liberia
… research leverages major ion and trace element analysis, Escherichia coli (E. coli) field tests, and high-throughput sequencing of microbial 16S rRNA genes to address these gaps and develop a comprehensive snapshot of groundwater quality in the region surrounding Monrovia, the capital city. A …
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The Application of Machine Learning Methods to Portable X-Ray Fluorescence Data: A Case Study from Zwartfontein Farm, Northern Limb of the Bushveld Complex, South Africa
… thesis demonstrates how a workflow combining compositional data analysis, wavelet tessellation and machine learning can rapidly transform low-cost portable X-ray fluorescence (pXRF) data into interpretable geological information. The development of methods was tested, as a case study, on the …
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A social epidemiology of foodwork and home-prepared food
… consumption, using nationally representative data from UK adults to: 1) Investigate how a ‘lack’ of time, in the form of competing demands on and other uses for time, is associated with time allocated to foodwork; and 2) Explore the association between home-prepared food consumption and diet …