title: A nested random effects model analysis of child survival in Malawi

authors: Manda, Samuel Osmond Makandi

abstract: This thesis investigates child survival in Malawi using a modified Cox proportional hazards model which includes family and community random effects in addition to the fixed effect of the covariates. The parameters of the model are estimated using the Gibbs sampler, a Bayesian Markov Chain Monte Carlo (MCMC) method. We believe this to be the first time the method has been used for this type of data. The parameters are also estimated using the expectation-maximisation (EM) algorithm, a method that has previously been used to analyse this type of data. Both approaches were implemented in Fortran using the NAG routines.

The child survival data used in this study were collected as part of the 1992 Demographic and Health Survey (DHS) of Malawi. The women respondents were obtained through a two-stage cluster sampling procedure. The respondents were systematically interviewed about biological, social and demographic factors relating to all live births that had occurred during the previous five years. 

The results show that the covariates first birth, birth spacing, breastfeeding duration, maternal age, hospital birth and father’s education are important determinants of infant and early childhood survival in Malawi. The family and community frailty effect variances are modest in magnitude. The study also shows that child mortality varies more considerably across families than over communities after controlling for the observed covariates. Neglecting frailty biases estimates of the observed covariates slightly downwards, although the subsequent substantive findings are not markedly affected. The strength of the family random effect is grossly overestimated when community random frailty is ignored while that of the community random effect shows stability whether family random frailty is controlled or not.

The Gibbs sampler is shown to be an important alternative to the EM algorithm and other existing methods for estimating parameters in a multilevel hazards model. It allows the full Bayesian inference without the need to evaluate high-dimensional integrals. We obtain a random sample from the complete posterior distribution of all the parameters and hyperparameters whose behaviour can be studied over their range rather than only around the mode. The Gibbs sampler is computational intensive, but this fact has decreasing relevance due to the availability of very powerful computing equipment.

text: A nested random effects model analysis of child survival in Malawi This thesis investigates child survival in Malawi using a modified Cox proportional hazards model which includes family and community random effects in addition to the fixed effect of the covariates. The parameters of the model are estimated using the Gibbs sampler, a Bayesian Markov Chain Monte Carlo (MCMC) method. We believe this to be the first time the method has been used for this type of data. The parameters are also estimated using the expectation-maximisation (EM) algorithm, a method that has previously been used to analyse this type of data. Both approaches were implemented in Fortran using the NAG routines.

The child survival data used in this study were collected as part of the 1992 Demographic and Health Survey (DHS) of Malawi. The women respondents were obtained through a two-stage cluster sampling procedure. The respondents were systematically interviewed about biological, social and demographic factors relating to all live births that had occurred during the previous five years. 

The results show that the covariates first birth, birth spacing, breastfeeding duration, maternal age, hospital birth and father’s education are important determinants of infant and early childhood survival in Malawi. The family and community frailty effect variances are modest in magnitude. The study also shows that child mortality varies more considerably across families than over communities after controlling for the observed covariates. Neglecting frailty biases estimates of the observed covariates slightly downwards, although the subsequent substantive findings are not markedly affected. The strength of the family random effect is grossly overestimated when community random frailty is ignored while that of the community random effect shows stability whether family random frailty is controlled or not.

The Gibbs sampler is shown to be an important alternative to the EM algorithm and other existing methods for estimating parameters in a multilevel hazards model. It allows the full Bayesian inference without the need to evaluate high-dimensional integrals. We obtain a random sample from the complete posterior distribution of all the parameters and hyperparameters whose behaviour can be studied over their range rather than only around the mode. The Gibbs sampler is computational intensive, but this fact has decreasing relevance due to the availability of very powerful computing equipment.

year: 1998

title: The manufacture and mechanical properties of aligned long harakeke fibre reinforced epoxy composites

authors: Le, Tan Minh

subjects: compression moulding

abstract: Aligned long harakeke fibre reinforced epoxy composites were prepared using hand lay-up followed by compression moulding. Densities of harakeke fibre and epoxy resin were determined for the purpose of composite design. The evenness of composites fabricated by two different size moulds was compared. It was found that more even composites were produced when using a small mould than a big mould. In this work, the dependence of tensile and flexural properties of harakeke/epoxy composites on fibre content was also investigated. The results showed that the addition of fibre enhanced tensile properties of epoxy. The tensile strength and Young’s modulus increased with the volume fraction of harakeke fibre. The flexural strength and flexural modulus increased as the fibre volume fraction increased up to 0.4. Further addition of fibre did not result in an improvement of composite flexural properties.

text: The manufacture and mechanical properties of aligned long harakeke fibre reinforced epoxy composites Aligned long harakeke fibre reinforced epoxy composites were prepared using hand lay-up followed by compression moulding. Densities of harakeke fibre and epoxy resin were determined for the purpose of composite design. The evenness of composites fabricated by two different size moulds was compared. It was found that more even composites were produced when using a small mould than a big mould. In this work, the dependence of tensile and flexural properties of harakeke/epoxy composites on fibre content was also investigated. The results showed that the addition of fibre enhanced tensile properties of epoxy. The tensile strength and Young’s modulus increased with the volume fraction of harakeke fibre. The flexural strength and flexural modulus increased as the fibre volume fraction increased up to 0.4. Further addition of fibre did not result in an improvement of composite flexural properties.

year: 2012-07-09

title: Governance and legitimacy: Indigenous development in Aotearoa

authors: Dodd, Materoa

subjects: Māori governance

abstract: Within the indigenous paradigm lies a paradox over what constitutes legitimate Māori authority: Iwi structures are legitimated and recognised by the state, and traditional forms (for example, Hapū and Māori women), have had their authority diminished. Iwi authorities are colonial constructs that diminish the rights of Hapū and Māori women. The manner in which such constructs have come about generally has not involved tribewide debate over important issues in which Hapū and Māori women have an interest. For their legitimacy, emergent self-governing structures will need to be grounded in principles that ensure legitimate representation of Māori people and not socially constructed hybrids of a colonial past. Structures need to recognise Hapū and Māori women in the formulation, anything less than this will trigger a legitimation crisis.

text: Governance and legitimacy: Indigenous development in Aotearoa Within the indigenous paradigm lies a paradox over what constitutes legitimate Māori authority: Iwi structures are legitimated and recognised by the state, and traditional forms (for example, Hapū and Māori women), have had their authority diminished. Iwi authorities are colonial constructs that diminish the rights of Hapū and Māori women. The manner in which such constructs have come about generally has not involved tribewide debate over important issues in which Hapū and Māori women have an interest. For their legitimacy, emergent self-governing structures will need to be grounded in principles that ensure legitimate representation of Māori people and not socially constructed hybrids of a colonial past. Structures need to recognise Hapū and Māori women in the formulation, anything less than this will trigger a legitimation crisis.

year: 2000-10