Saudi Cultural Missions Theses & Dissertations
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Item Restricted The Development of Correspondence Analysis Techniques using the Family of Cressie–Read Power Divergence Statistics(The University of Newcastle, 2024-03-14) Alzahrani, Asma; Beh, Eric; Stojanovski, ElizabethCorrespondence analysis (CA) is a visual statistical technique that has a long and interesting history. It is a powerful multivariate statistical technique that aims to uncover underlying patterns and associations between two or more categorical variables. As datasets continue to expand in complexity and size, there is a growing need for advanced analytical techniques that can handle and extract meaningful insights from such data. The classical approach to CA considers Pearson’s chi-squared statistic as the fundamental measure of association between categorical variables. However, this thesis provides an extension to CA techniques by employing the family of Cressie-Read divergence statistics as a measure to examine the association between the categorical variables. This family includes the most common statistics of association such as Pearson’s statistic, the Freeman-Tukey statistic, the log-likelihood ratio statistic, and the Cressie-Read statistic. Thus, by using the family of Cressie- Read divergence statistics to conduct CA, a more comprehensive understanding can be obtained, which expands the analysis beyond Pearson’s statistic. This thesis describes this approach to CA in detail and highlights its features by providing various applications. Moreover, we further generalise the approach to enable the analysis of multiple categorical variables. A new technique for constructing confidence regions based on the family of Cressie-Read divergence statistics is also explored. Further extensions of this area of CA are also made by showing how it can be used to analyse the association between the variables of a multi-way contingency table. The results of such analyses allow for a highly effective visual exploration of the association structure between categorical variables. Additionally, R functions for all techniques discussed in the thesis are provided. This, in turn, provides a significant contribution for researchers wanting to increase their flexibility in programming and create new and powerful tools for categorical data analysis42 0Item Restricted The Association Between Weight Loss and Periodontal Inflammation(Saudi Digital Library, 2023-12-01) Khoja, Fay; Suvan, JeanieBackground: Evidence reports an association between obesity and periodontal disease, however minimal research exists regarding the possible impact of weight loss through diet or bariatric surgery on periodontal condition. The aim of this study was to investigate the effect of weight loss through diet or surgery on periodontal health. Method: This study was a single centre quasi-experimental study with 6- and 12- weeks follow up recruited patients allocated to two groups; diet route and bariatric surgery route. Dental, social history, and periodontal examinations were carried out for each participant to determine their periodontal status. Masticatory function was assessed objectively (masticatory efficiency) using a validated colour-mixing chewing assessment and a validated self-reported questionnaire exploring participants oral health perception questionnaire (Dental habits, Obesity stigma in dental office, masticatory ability). Patient subsequently received bariatric surgery or a 12-week low-calorie diet. Six- and twelve-weeks following surgery or diet, the clinical and masticatory assessments were repeated. Results: This thesis will present partial findings of the ongoing study. The study recruited 7 participants living with obesity (4 in the diet group, 3 in the surgery group) all participants were recruited for baseline assessment, and 2 reported 6 weeks follow up (one from each group). The mean age in years within surgery and diet groups was 35.29 SD± 8.38, with weight mean range of 136.80 Kg SD± 10.3 and 129.53 Kg SD± 6.35 for surgery and diet groups respectively. Questionnaire analysis for obesity stigma in the dental office demonstrated 28.6% avoided dental care treatment due to feeling uncomfortable and reported that a dental care provider critiqued or insulted them regarding their weight. Conclusions: Due to the ongoing nature of this study, no conclusion can be reported regarding the influence of weight loss on the periodontal status. The self-reported questionnaire reported that one third of the enrolled participants faced discrimination related to their weight in the dental office.4 0