Bayesian spatio-temporal zero-inflated mixed models for overdispersion on chronic disease mapping
- Osuji, Georgeleen O https://orcid.org/0000-0002-8408-3928
- Authors: Osuji, Georgeleen O https://orcid.org/0000-0002-8408-3928
- Date: 2021-12
- Subjects: Medical mapping , Bayesian statistical decision theory
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23644 , vital:58230
- Description: Background: Life expectancy in most developing countries has remarkably increased and decreased in mortality, but under 5 years old mortality has increased due to HIV and Tuberculosis incidence. Many factors have been established to influence the mortality rate among HIV patients and understanding the factors contribution to the risk of under 5-year-old mortality is important for designing appropriate health interventions. Excess zeros usually occur in such HIV mortality count data. Mixed models consisting of count part and zero part are often used to describe the observed excess zero in the data. Poisson models are popular modeling inference, but Negative-Binomial models are more flexible in analyzing count data and dealing with overdispersion. Method: This research proposed to develop two-part hurdle models in analyzing areal zero count data. A spatial Bayesian lognormal-logit hurdle model (BLLHM) with random effects characterizes and cross-spatial dependencies were introduced. The parameter inferences and predictions were evaluated using the Markov Chain Monte Carlo algorithm. The model proposed was applied to HIV-positive under 5-year-old mortality collected from the Eastern Cape Department of Health. Results: Bayesian lognormal-logit hurdle model is selected as the best model fit. It is observed that the total number of HIV patients not on ART-HIVnotTB (0.000612, p <0.000) was positively and statistically significantly associated with the HIV-positive mortality of under 5 years patients. Both CD4 counts were done on newly diagnosed HIV rate (CD4count) and HIV-positive new patients screened for TB rate (HIVTBrate) were negatively and statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.6294, p = 0.000 and -0.00056, p = 0.0052). However, the covariate HIV positive Tuberculosis Preventive therapy (TPT) uptake rate (HIVandTB) was not statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.00155, p = 0.5392). Conclusion: The model is flexible to deal with zero-inflated and over-dispersed count data. There is a need to consider the risk of cause-specific under-5-year-old mortality in terms of spatial effects. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Osuji, Georgeleen O https://orcid.org/0000-0002-8408-3928
- Date: 2021-12
- Subjects: Medical mapping , Bayesian statistical decision theory
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23644 , vital:58230
- Description: Background: Life expectancy in most developing countries has remarkably increased and decreased in mortality, but under 5 years old mortality has increased due to HIV and Tuberculosis incidence. Many factors have been established to influence the mortality rate among HIV patients and understanding the factors contribution to the risk of under 5-year-old mortality is important for designing appropriate health interventions. Excess zeros usually occur in such HIV mortality count data. Mixed models consisting of count part and zero part are often used to describe the observed excess zero in the data. Poisson models are popular modeling inference, but Negative-Binomial models are more flexible in analyzing count data and dealing with overdispersion. Method: This research proposed to develop two-part hurdle models in analyzing areal zero count data. A spatial Bayesian lognormal-logit hurdle model (BLLHM) with random effects characterizes and cross-spatial dependencies were introduced. The parameter inferences and predictions were evaluated using the Markov Chain Monte Carlo algorithm. The model proposed was applied to HIV-positive under 5-year-old mortality collected from the Eastern Cape Department of Health. Results: Bayesian lognormal-logit hurdle model is selected as the best model fit. It is observed that the total number of HIV patients not on ART-HIVnotTB (0.000612, p <0.000) was positively and statistically significantly associated with the HIV-positive mortality of under 5 years patients. Both CD4 counts were done on newly diagnosed HIV rate (CD4count) and HIV-positive new patients screened for TB rate (HIVTBrate) were negatively and statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.6294, p = 0.000 and -0.00056, p = 0.0052). However, the covariate HIV positive Tuberculosis Preventive therapy (TPT) uptake rate (HIVandTB) was not statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.00155, p = 0.5392). Conclusion: The model is flexible to deal with zero-inflated and over-dispersed count data. There is a need to consider the risk of cause-specific under-5-year-old mortality in terms of spatial effects. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-12
Investigation of institutions for the implementation of the Dutywa Agripark Project in Mbashe Local Municipality in Eastern Cape Province, South Africa
- Authors: Ndita, Bongani Herschel
- Date: 2013
- Subjects: Agricultural development projects , Rangelands
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24587 , vital:63210
- Description: The study investigated local institutions amongst Agri-park project beneficiaries: A case of Dutywa Agri-park in Mbashe Local Municipality. Specifically, the dissertation sought to: investigate formal and informal institutions pertaining to land, rangeland management and support services, extension services amongst Agri-park beneficiaries, and explore options with communities to strengthen these institutions for the application of the Agri-park projects. The role of local institutions in economic development has received steadily increasing attention from researchers, policy makers and development practitioners. , institutions can be defined as the formal and informal rules of the game that have been formulated to rule people‟s behaviour and transactions. Informal rules may include among others, customs, norms and standards, religion, indigenous law while formal rules may include laws, constitutions, policies, markets and firms. This study used a survey design, quantitative and qualitative research methodologies involving the use of questionnaire. The data for this study was collected from 114 households which are Agri-park project beneficiaries, the extension officer, project site manager and local economic development officer. The data were collected through face to face and telephonic interviews. Institutional Analysis and Development (IAD) framework and Statistical Package for Social Sciences (SPSS version 20.0) were used for descriptive analysis in order to identify the existing local institutions and how they should be strengthen. The results showed that a number of local institutions do exist. The main findings of this study were as follows: (1) Project beneficiaries were aware of their stakeholders and that they knew the roles and responsibilities of each stakeholder in the project. (2) Traditional leaders were aware about the project and that they have a major role to play. (3) Project beneficiaries have organized themselves into groups of co-operatives and their co-operatives are registered with the Department of Agriculture. (4) Project initiators are going to transfer the ownership of the project to these communities after it becomes well established. (5) There was a mutual agreement of youth employment rotation in the project between these four communities. (6) The condition of lease agreement for a land where the project currently running is 9 months renewable contract with the rental payment of R 6300.00 per annum. (7) The lease agreement gives the church a property right to reclaim the land should payments not be made. (8) Project beneficiaries possess some agricultural skills and that they have received various training. The study recommended that there is a need to strengthen these rules and regulation for the project to become more efficient and productive in the long-run. , Thesis (MSc) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
- Authors: Ndita, Bongani Herschel
- Date: 2013
- Subjects: Agricultural development projects , Rangelands
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24587 , vital:63210
- Description: The study investigated local institutions amongst Agri-park project beneficiaries: A case of Dutywa Agri-park in Mbashe Local Municipality. Specifically, the dissertation sought to: investigate formal and informal institutions pertaining to land, rangeland management and support services, extension services amongst Agri-park beneficiaries, and explore options with communities to strengthen these institutions for the application of the Agri-park projects. The role of local institutions in economic development has received steadily increasing attention from researchers, policy makers and development practitioners. , institutions can be defined as the formal and informal rules of the game that have been formulated to rule people‟s behaviour and transactions. Informal rules may include among others, customs, norms and standards, religion, indigenous law while formal rules may include laws, constitutions, policies, markets and firms. This study used a survey design, quantitative and qualitative research methodologies involving the use of questionnaire. The data for this study was collected from 114 households which are Agri-park project beneficiaries, the extension officer, project site manager and local economic development officer. The data were collected through face to face and telephonic interviews. Institutional Analysis and Development (IAD) framework and Statistical Package for Social Sciences (SPSS version 20.0) were used for descriptive analysis in order to identify the existing local institutions and how they should be strengthen. The results showed that a number of local institutions do exist. The main findings of this study were as follows: (1) Project beneficiaries were aware of their stakeholders and that they knew the roles and responsibilities of each stakeholder in the project. (2) Traditional leaders were aware about the project and that they have a major role to play. (3) Project beneficiaries have organized themselves into groups of co-operatives and their co-operatives are registered with the Department of Agriculture. (4) Project initiators are going to transfer the ownership of the project to these communities after it becomes well established. (5) There was a mutual agreement of youth employment rotation in the project between these four communities. (6) The condition of lease agreement for a land where the project currently running is 9 months renewable contract with the rental payment of R 6300.00 per annum. (7) The lease agreement gives the church a property right to reclaim the land should payments not be made. (8) Project beneficiaries possess some agricultural skills and that they have received various training. The study recommended that there is a need to strengthen these rules and regulation for the project to become more efficient and productive in the long-run. , Thesis (MSc) -- Faculty of Science and Agriculture, 2013
- Full Text:
- Date Issued: 2013
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