title: Comparing classical criteria for selecting intra-class correlated features in Multimix

authors: Hunt, Lynette Anne

subjects: Science & Technology

abstract: The mixture approach to clustering requires the user to specify both the number of components to be fitted to the model and the form of the component distributions. In the Multimix class of models, the user also has to decide on the correlation structure to be introduced into the model. The behaviour of some commonly used model selection criteria is investigated when using the finite mixture model to cluster data containing mixed categorical and continuous attributes. The performance of these criteria in selecting both the number of components in the model and the form of the correlation structure amongst the attributes when fitting the Multimix class of models is illustrated using simulated data and a real medical data set. It is found that criteria based on the integrated classification likelihood have the best performance in detecting the number of clusters to be fitted to the model and in selecting the form of the component distributions. The performance of the Bayesian information criterion in detecting the correct model depends on the partitioning structure among the attributes while the Akaike information criterion and classification likelihood criterion perform in a less satisfactory way.

text: Comparing classical criteria for selecting intra-class correlated features in Multimix The mixture approach to clustering requires the user to specify both the number of components to be fitted to the model and the form of the component distributions. In the Multimix class of models, the user also has to decide on the correlation structure to be introduced into the model. The behaviour of some commonly used model selection criteria is investigated when using the finite mixture model to cluster data containing mixed categorical and continuous attributes. The performance of these criteria in selecting both the number of components in the model and the form of the correlation structure amongst the attributes when fitting the Multimix class of models is illustrated using simulated data and a real medical data set. It is found that criteria based on the integrated classification likelihood have the best performance in detecting the number of clusters to be fitted to the model and in selecting the form of the component distributions. The performance of the Bayesian information criterion in detecting the correct model depends on the partitioning structure among the attributes while the Akaike information criterion and classification likelihood criterion perform in a less satisfactory way.

year: 2016

title: Genetic Diversity and Structure in the Philippine Rafflesia lagascae Complex (Rafflesiaceae) inform its Taxonomic Delimitation and Conservation

authors: Pelser, Pieter B.

subjects: Microsatellites

abstract: Rafflesia lagascae (Rafflesiaceae) is a rare endo-holoparasitic plant species with a disjunct distribution on Luzon Island in the Philippines. It is morphologically very similar to R. manillana, which is only known from a single population on nearby Samar Island. This study aims to contribute to the taxonomy and conservation of R. lagascae and R. manillana (i.e., the R. lagascae complex) by resolving their patterns of genetic diversity and genetic structure. The results of population genetic analyses of a microsatellite data set indicate that despite their frequently extremely small sizes and geographic isolation, Rafflesia populations display moderate genetic diversity and do not show evidence of pronounced inbreeding. Most populations appear to be strongly genetically differentiated from each other, suggesting limited gene flow between them. Patterns of genetic diversity of staminate and pistillate Rafflesia flowers growing on the same Tetrastigma host plants indicate that the R. lagascae complex is monoecious and that host plants are regularly infected by more than one Rafflesia plant. Both might enable Rafflesia to maintain viable populations in areas with low host densities. PCoA and Bayesian cluster analyses show that the R. lagascae complex is composed of three genetically isolated taxa. One of these constitutes R. manillana, supporting the morphology-based hypothesis that it is taxonomically distinct from R. lagascae. The second taxon in this complex is composed of the single population of R. lagascae from Mt. Labo. This morphologically cryptic population is genetically distinct from the 11 remaining R. lagascae populations that were included in this study and that form the third taxon. We recommend that R. lagascae s. s., the Mt. Labo R. lagascae, and R. manillana should be managed as different conservation entities.

text: Genetic Diversity and Structure in the Philippine Rafflesia lagascae Complex (Rafflesiaceae) inform its Taxonomic Delimitation and Conservation Rafflesia lagascae (Rafflesiaceae) is a rare endo-holoparasitic plant species with a disjunct distribution on Luzon Island in the Philippines. It is morphologically very similar to R. manillana, which is only known from a single population on nearby Samar Island. This study aims to contribute to the taxonomy and conservation of R. lagascae and R. manillana (i.e., the R. lagascae complex) by resolving their patterns of genetic diversity and genetic structure. The results of population genetic analyses of a microsatellite data set indicate that despite their frequently extremely small sizes and geographic isolation, Rafflesia populations display moderate genetic diversity and do not show evidence of pronounced inbreeding. Most populations appear to be strongly genetically differentiated from each other, suggesting limited gene flow between them. Patterns of genetic diversity of staminate and pistillate Rafflesia flowers growing on the same Tetrastigma host plants indicate that the R. lagascae complex is monoecious and that host plants are regularly infected by more than one Rafflesia plant. Both might enable Rafflesia to maintain viable populations in areas with low host densities. PCoA and Bayesian cluster analyses show that the R. lagascae complex is composed of three genetically isolated taxa. One of these constitutes R. manillana, supporting the morphology-based hypothesis that it is taxonomically distinct from R. lagascae. The second taxon in this complex is composed of the single population of R. lagascae from Mt. Labo. This morphologically cryptic population is genetically distinct from the 11 remaining R. lagascae populations that were included in this study and that form the third taxon. We recommend that R. lagascae s. s., the Mt. Labo R. lagascae, and R. manillana should be managed as different conservation entities.

year: 2017

title: Decolonising Pākehā ways of being: Revealing third space Pākehā experiences

authors: Brown, Micheal William

subjects: Pakeha

abstract: This thesis asks two central questions. First, what kinds of experiences occur when Pākehā become interested and involved in te ao Māori (the Māori world)? Second, how might sharing of these experiences help other Pākehā better understand their relationship with Māori? The account is grounded in concepts of colonisation and the coloniser/colonised relation, Othering, Whiteness, hybridity and the third space, biculturalism, theories of movement between groups, and decolonisation. It particularly drew on Homi Bhabha’s notions of the third space to theorise and explain the process of change that occurred for 13 Pākehā involved in te ao Māori. Utilising a qualitative design based on grounded theory and in-depth interviewing the research investigated their “lived” experiences and their choice to encounter then engage with te ao Māori. It is their experiences that I interpret in this thesis as “third space Pākehā experiences”. Through my employment of grounded theory methodology to analyse the korero (stories) I collected, I argue that a transformative process of change occurred for the 13 participants because they became interested and engaged more in ongoing experiences of te ao Māori. I interpreted this process as “Pākehā decolonisation”. In my analysis I found that at the individual level decolonisation helped these Pākehā bridge gaps that emerged as “differences” between te ao Māori and te ao Pākehā which led them to develop a new and enriched understanding of themselves. Their engagement with te ao Māori produced exciting and rewarding experiences, the richness of these is revealed in the storylines. Also, their ongoing experiences moved towards effective strategies to engage in discussions with other Pākehā about te ao Māori, which were respectful to both Māori and Pākehā cultures. I interpreted this development as the “Pākehā educating Pākehā” strategy. My analysis also suggested that five key thematic elements - or what I call five “occurrences” of Pākehā decolonisation, existed within each participant’s third space experiences. They were: 1) all participants chose to engage in many diverse encounters with te ao Māori, 2) this led the individual to their discovery of ngā wairua o te ao Māori (values of the Māori world), 3) as well as to experiencing Othering experiences from Pākehā, 4) the ongoing choice to engage with te ao Māori developed into awareness and experience of sites/locations where equality between Māori and Pākehā existed and, 5) and it was through confrontational experiences that these Pākehā began to learn successful Pākehā educating Pākehā strategies which they employed when engaging with other Pākehā about te ao Māori. These five occurrences happened frequently and infrequently across participants and they occurred in multiple settings as well as during different decades of their lives. Nonetheless, the choice to enter into these experience(s), whether at the time of occurrence - or on reflection at a later stage - emerged as a defining of their “journey” into te ao Māori; a journey of enriched, insightful and meaningful experiences that helped these Pākehā develop a more sophisticated understanding of te ao Māori and their relationship to Māori within that world. Thus, these Pākehā discovered that exploration into te ao Māori was a benefit to themselves as individual Pākehā. This thesis is an applied research study that draws from Homi Bhabha’s (1994) theory/concept of hybridity and movement between groups. I employed this approach because I was concerned with movement by a group member (Pākehā) toward another group (Māori). The research conceptualises Bhabha’s (1994) “third space” as an “experience” rather than a permanent positioning and explores ways in which change occurs for non hybrid group members who engage in the third space experience and, that a third space vocabulary exists for talking about shared experiences that does not put one’s own identity at risk. The main contributions of this research are threefold. Firstly, when Pākehā enter into te ao Māori they encounter third space experiences that reveal new and enriched ways to experience te ao Māori, and they develop a more sophisticated view of the Māori and Pākehā coloniser/colonial relation, its history, as well as present relations and pathways for future equal engagement. Secondly, third space experiences offer a “way forward” for Māori and Pākehā relationships that suggests an alternative to contestation and confrontation. Third, third space experiences provide a pathway toward a Pākehā educating Pākehā strategy; an accessible and practical outcome of a positive and rewarding alternative decolonisation process which helps other Pākehā discover a deeper understanding of their place in New Zealand. I argue that decolonisation and the Pākehā educating Pākehā strategy helps Pākehā learn from their lived experiences of “being Pākehā” - a phrase coined by historian Michael King (1985, 1999b).

text: Decolonising Pākehā ways of being: Revealing third space Pākehā experiences This thesis asks two central questions. First, what kinds of experiences occur when Pākehā become interested and involved in te ao Māori (the Māori world)? Second, how might sharing of these experiences help other Pākehā better understand their relationship with Māori? The account is grounded in concepts of colonisation and the coloniser/colonised relation, Othering, Whiteness, hybridity and the third space, biculturalism, theories of movement between groups, and decolonisation. It particularly drew on Homi Bhabha’s notions of the third space to theorise and explain the process of change that occurred for 13 Pākehā involved in te ao Māori. Utilising a qualitative design based on grounded theory and in-depth interviewing the research investigated their “lived” experiences and their choice to encounter then engage with te ao Māori. It is their experiences that I interpret in this thesis as “third space Pākehā experiences”. Through my employment of grounded theory methodology to analyse the korero (stories) I collected, I argue that a transformative process of change occurred for the 13 participants because they became interested and engaged more in ongoing experiences of te ao Māori. I interpreted this process as “Pākehā decolonisation”. In my analysis I found that at the individual level decolonisation helped these Pākehā bridge gaps that emerged as “differences” between te ao Māori and te ao Pākehā which led them to develop a new and enriched understanding of themselves. Their engagement with te ao Māori produced exciting and rewarding experiences, the richness of these is revealed in the storylines. Also, their ongoing experiences moved towards effective strategies to engage in discussions with other Pākehā about te ao Māori, which were respectful to both Māori and Pākehā cultures. I interpreted this development as the “Pākehā educating Pākehā” strategy. My analysis also suggested that five key thematic elements - or what I call five “occurrences” of Pākehā decolonisation, existed within each participant’s third space experiences. They were: 1) all participants chose to engage in many diverse encounters with te ao Māori, 2) this led the individual to their discovery of ngā wairua o te ao Māori (values of the Māori world), 3) as well as to experiencing Othering experiences from Pākehā, 4) the ongoing choice to engage with te ao Māori developed into awareness and experience of sites/locations where equality between Māori and Pākehā existed and, 5) and it was through confrontational experiences that these Pākehā began to learn successful Pākehā educating Pākehā strategies which they employed when engaging with other Pākehā about te ao Māori. These five occurrences happened frequently and infrequently across participants and they occurred in multiple settings as well as during different decades of their lives. Nonetheless, the choice to enter into these experience(s), whether at the time of occurrence - or on reflection at a later stage - emerged as a defining of their “journey” into te ao Māori; a journey of enriched, insightful and meaningful experiences that helped these Pākehā develop a more sophisticated understanding of te ao Māori and their relationship to Māori within that world. Thus, these Pākehā discovered that exploration into te ao Māori was a benefit to themselves as individual Pākehā. This thesis is an applied research study that draws from Homi Bhabha’s (1994) theory/concept of hybridity and movement between groups. I employed this approach because I was concerned with movement by a group member (Pākehā) toward another group (Māori). The research conceptualises Bhabha’s (1994) “third space” as an “experience” rather than a permanent positioning and explores ways in which change occurs for non hybrid group members who engage in the third space experience and, that a third space vocabulary exists for talking about shared experiences that does not put one’s own identity at risk. The main contributions of this research are threefold. Firstly, when Pākehā enter into te ao Māori they encounter third space experiences that reveal new and enriched ways to experience te ao Māori, and they develop a more sophisticated view of the Māori and Pākehā coloniser/colonial relation, its history, as well as present relations and pathways for future equal engagement. Secondly, third space experiences offer a “way forward” for Māori and Pākehā relationships that suggests an alternative to contestation and confrontation. Third, third space experiences provide a pathway toward a Pākehā educating Pākehā strategy; an accessible and practical outcome of a positive and rewarding alternative decolonisation process which helps other Pākehā discover a deeper understanding of their place in New Zealand. I argue that decolonisation and the Pākehā educating Pākehā strategy helps Pākehā learn from their lived experiences of “being Pākehā” - a phrase coined by historian Michael King (1985, 1999b).

year: 2011