Research Doctorate - Doctor of Philosophy (PhD) / The rapid pace of growth in the field of human genetics has left researchers with many new challenges in the area of security and privacy. To encourage participation and foster trust towards research, it is important to ensure that genetic databases are adequately protected. This task is a particularly challenging one for statistical agencies due to the high prevalence of categorical data contained within statistical genetic databases. The absence of natural ordering makes the application of traditional Statistical Disclosure Control (SDC) methods less straightforward, which is why we have proposed a new noise addition technique for categorical values. The main contributions of the thesis are as follows. We provide a comprehensive analysis of the trust relationships that occur between the different stakeholders in a genetic data warehouse system. We also provide a quantifiable model of trust that allows the database manager to granulate the level of protection based on the amount of trust that exists between the stakeholders. To the best of our knowledge, this is the first time that trust has been applied in the SDC context. We propose a privacy protection framework for genetic databases which is designed to deal with the fact that genetic data warehouses typically contain a high proportion of categorical data. The framework includes the use of a clustering technique which allows for the easier application of traditional noise addition techniques for categorical values. Another important contribution of this thesis is a new similarity measure for categorical values, which aims to capture not only the direct similarity between values, but also some sense of transitive similarity. This novel measure also has possible applications in providing a way of ordering categorical values, so that more traditional SDC methods can be more easily applied to them. Our analysis of experimental results also points to a numerical attribute phenomenon, whereby we typically have high similarity between numerical values that are close together, and where the similarity decreases as the absolute value of the difference between numerical values increases. However, some numerical attributes appear to not behave in a strictly `numerical' way. That is, values which are close together numerically do not always appear very similar. We also provide a novel noise addition technique for categorical values, which employs our similarity measure to partition the values in the data set. Our method - VICUS - then perturbs the original microdata file so that each value is more likely to be changed to another value in the same partition than one from a different partition. The technique helps to ensure that the perturbed microdata file retains data quality while also preserving the privacy of individual records.

Research Doctorate - Doctor of Philosophy (PhD) / The rapid pace of growth in the field of human genetics has left researchers with many new challenges in the area of security and privacy. To encourage participation and foster trust towards research, it is important to ensure that genetic databases are adequately protected. This task is a particularly challenging one for statistical agencies due to the high prevalence of categorical data contained within statistical genetic databases. The absence of natural ordering makes the application of traditional Statistical Disclosure Control (SDC) methods less straightforward, which is why we have proposed a new noise addition technique for categorical values. The main contributions of the thesis are as follows. We provide a comprehensive analysis of the trust relationships that occur between the different stakeholders in a genetic data warehouse system. We also provide a quantifiable model of trust that allows the database manager to granulate the level of protection based on the amount of trust that exists between the stakeholders. To the best of our knowledge, this is the first time that trust has been applied in the SDC context. We propose a privacy protection framework for genetic databases which is designed to deal with the fact that genetic data warehouses typically contain a high proportion of categorical data. The framework includes the use of a clustering technique which allows for the easier application of traditional noise addition techniques for categorical values. Another important contribution of this thesis is a new similarity measure for categorical values, which aims to capture not only the direct similarity between values, but also some sense of transitive similarity. This novel measure also has possible applications in providing a way of ordering categorical values, so that more traditional SDC methods can be more easily applied to them. Our analysis of experimental results also points to a numerical attribute phenomenon, whereby we typically have high similarity between numerical values that are close together, and where the similarity decreases as the absolute value of the difference between numerical values increases. However, some numerical attributes appear to not behave in a strictly `numerical' way. That is, values which are close together numerically do not always appear very similar. We also provide a novel noise addition technique for categorical values, which employs our similarity measure to partition the values in the data set. Our method - VICUS - then perturbs the original microdata file so that each value is more likely to be changed to another value in the same partition than one from a different partition. The technique helps to ensure that the perturbed microdata file retains data quality while also preserving the privacy of individual records.

Research Doctorate - Doctor of Philosophy (PhD) / Privacy of personal information is becoming a major problem in health care, in the light of coming implementation of electronic health record (EHR)systems. There is evidence of increasing public concern over privacy of personal health information that is to be stored in EHRs and widely used within the interconnected systems. The issues for the health care system include inadequate legislation for privacy in health care, as well as deficiency of effective technical and security measures. The work in the thesis is part of a larger project which aims to offer a comprehensive set of new techniques for protection of confidential individual's health data used for statistical purposes. The research strategy is to explore concerns about privacy in relation to legislation, attitudes to health care and technical protections in statistical databases. It comprised two different approaches: * content analysis of legal frameworks addressing protection of privacy in Australian health care, and * social research to explore privacy concerns in health care by Australians 18 years and over. This thesis presents a new multi-stage research to explore privacy concerns in health care raised by the development of EHR systems. Stage one involved 23 participants within four focus groups. Stage two was a national sample survey conducted with 700 respondents 18 years and over. The results of analysis are presented. They are compared with the results of other studies. The main findings of this thesis are: * revealing the main inadequacies in the Australian legal system for protecting privacy of health information in electronic health records; * determining characteristics of people who have concerns about the privacy of their health information; * identifying items of a health record which have to be protected and some reasons for that. The findings of the study will assist with the decision and solution for appropriate technical measures in statistical databases as well as issues of inadequacy in the existing privacy legislation. Furthermore, the work in this thesis confirmed a low awareness of public in relation to statistical use of personal health information and a low level of trust to automated systems of electronic health records which are initiated by the government. In conclusion, attitude towards privacy depends on individual's characteristics but also on existing legislation, public's awareness of this legislation,the means of resolving complaints, and awareness of technical means for privacy protection. Therefore, it is important to educate public in order for EHR system function to the full of its potential and the future innovations of information technology to strengthen health care and medical research.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2015-10-13T12:03:31Z No. of bitstreams: 2 Dissertação - Flávio Cavarsan - 2014.pdf: 2147420 bytes, checksum: 4c71cd47ba4580423701808c54260308 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-10-13T12:26:12Z (GMT) No. of bitstreams: 2 Dissertação - Flávio Cavarsan - 2014.pdf: 2147420 bytes, checksum: 4c71cd47ba4580423701808c54260308 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-10-13T12:26:12Z (GMT). No. of bitstreams: 2 Dissertação - Flávio Cavarsan - 2014.pdf: 2147420 bytes, checksum: 4c71cd47ba4580423701808c54260308 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-11-21 / Objective: To analyze the temporal evolution of incidence and trends of skin cancer, either melanoma and nonmelanoma lesions, in the city of Goiania during the period from 1998 to 2008. Methods: From January 1988 to December 2008, all malignant skin tumours of the city of Goiania (Brazil), registered by the Population Based Cancer Register of Goiania were accessed. The cases were stratified according to gender, age, morphology and anatomical site. The proportions, crude coefficients and incidence rates were calculated using the SPSS version 18 software, while Poison's regression model was obtained by Joinpoint software. Results: Twenty six thousand nine hundred and eighty-eight registers of skin cancer were found, 19,961 basal cell carcinomas (BCC), 6,156 squamous cell carcinomas (SCC) and 871 cutaneous melanomas (CM). Histological confirmation was performed in more than 98% of the cases. A significant trend of increasing incidence associated to age was observed in men with SCC (APC=6.6%) and CM (APC=9.8%). The same trend was identified for women with CM (APC=7.7%). A rising incidence related to age was found. Nonmelanomas skin tumours occurred more often on face, while the trunk was more common for melanomas. Conclusions: The incidence of BCC was stable for both genders in Goiania during the study period. In the other hand, it was observed an increasing incidence for CM in men and women, and SCC showed a raise in incidence only for males. The age above 50s is a risk factor for increasing incidence of skin cancer. The trunk and face were the most common sites of either SCC and BCC, while cutaneous melanomas were more often on the trunk and limbs. Prevention through a complete physical exam is the best action for early detection of skin lesions; as well information regarding the risks of excess chronic sun exposition is the best primary prevention method. / Objetivo: Analisar a evolução temporal da incidência e a tendência das neoplasias cutâneas, não melanoma e melanoma no município de Goiânia no período de 1998 a 2008. Metodologia: Foram alvos do estudo os casos registrados de neoplasias malignas de pele de residentes de Goiânia, no período de 1988 – 2008, identificados pelo Registro de Câncer de Base Populacional de Goiânia. Os casos foram estratificados por gênero, grupo etário, morfologia e localização anatômica. Realizaram-se os cálculos das proporções, coeficientes brutos e padronizados de incidência. Utilizou-se o programa SPSS versão 18 e para as análises de tendências, o modelo de regressão linear do programa Joinpoint. Resultados: Foram observados 26.988 casos registrados de neoplasias de pele, com 19.961 carcinomas basocelulares (CBC), 6.156 carcinomas espinocelulares (CEC) e 871 melanomas cutâneos (MC); em mais de 98% dos casos houve confirmação histológica; observou-se tendência de aumento de incidência significante para homens com CEC (APC = 6,6%) e MC (APC = 9,8%) e para mulheres com MC (APC = 7,7%). Houve aumento de incidência com a idade. A face foi o local mais comum entre as neoplasias não melanomas, enquanto o tronco foi o mais comum nos melanomas. Conclusões: A incidência do CBC está estável em homens e mulheres em Goiânia. Para os CEC a incidência está aumentando nos homens enquanto nos MC houve aumento nos dois sexos, maior entre os homens. A idade é um fator de risco após 50 anos com maior aumento de incidência. A face e o tronco foram as localizações mais incidentes para CBC e CEC. Nos melanomas o aumento foi em tronco e membros. A prevenção com exame clínico de todo o tegumento é a melhor recomendação para o diagnóstico precoce do câncer de pele não melanoma e melanoma cutâneo. Medidas de orientação quanto a exposição solar são recomendas na prevenção primária.

Statistical data, such as in the form of microdata, is used by different organisations as a basis for creating knowledge to assist in their planning and decision-making activities. However, before microdata can be made available for analysis, it needs to be anonymised in order to protect the privacy of the individuals whose data is released. The protection of privacy requires us to hide or obscure the released data. On the other hand, making data useful for its users implies that we should provide data that is accurate, complete and precise. Ideally, we should maximise both the level of privacy and the level of information utility of a released microdata set. However, as we increase the level of privacy, the level of information utility decreases. Without guidelines to guide the selection of the optimum levels of privacy and information utility, it is difficult to determine the optimum balance between the two goals. The objective and constraints of this optimisation problem can be captured naturally with concepts from Economic Price Theory. In this thesis, we present an approach based on Economic Price Theory for guiding the process of microdata anonymisation such that optimum levels of privacy and information utility are achieved. / Thesis (PhD)--University of Pretoria, 2010. / Computer Science / unrestricted