title: Bagging ensemble selection for regression

authors: Sun, Quan

subjects: Machine learning

abstract: Bagging ensemble selection (BES) is a relatively new ensemble learning strategy. The strategy can be seen as an ensemble of the ensemble selection from libraries of models (ES) strategy. Previous experimental results on binary classiﬁcation problems have shown that using random trees as base classiﬁers, BES-OOB (the most successful variant of BES) is competitive with (and in many cases, superior to) other ensemble learning strategies, for instance, the original ES algorithm, stacking with linear regression, random forests or boosting. Motivated by the promising results in classiﬁcation, this paper examines the predictive performance of the BES-OOB strategy for regression problems. Our results show that the BES-OOB strategy outperforms Stochastic Gradient Boosting and Bagging when using regression trees as the base learners. Our results also suggest that the advantage of using a diverse model library becomes clear when the model library size is relatively large. We also present encouraging results indicating that the non negative least squares algorithm is a viable approach for pruning an ensemble of ensembles.

text: Bagging ensemble selection for regression Bagging ensemble selection (BES) is a relatively new ensemble learning strategy. The strategy can be seen as an ensemble of the ensemble selection from libraries of models (ES) strategy. Previous experimental results on binary classiﬁcation problems have shown that using random trees as base classiﬁers, BES-OOB (the most successful variant of BES) is competitive with (and in many cases, superior to) other ensemble learning strategies, for instance, the original ES algorithm, stacking with linear regression, random forests or boosting. Motivated by the promising results in classiﬁcation, this paper examines the predictive performance of the BES-OOB strategy for regression problems. Our results show that the BES-OOB strategy outperforms Stochastic Gradient Boosting and Bagging when using regression trees as the base learners. Our results also suggest that the advantage of using a diverse model library becomes clear when the model library size is relatively large. We also present encouraging results indicating that the non negative least squares algorithm is a viable approach for pruning an ensemble of ensembles.

year: 2012

title: Epibiotic pressure contributes to biofouling invader success

authors: Leonard, Kaeden

abstract: Reduced competition is a frequent explanation for the success of many introduced species. In benthic marine biofouling communities, space limitation leads to high rates of overgrowth competition. Some species can utilise other living organisms as substrate (epibiosis), proffering a competitive advantage for the epibiont. Additionally, some species can prevent or reduce epibiotic settlement on their surfaces and avoid being basibionts. To test whether epibiotic pressure differs between native and introduced species, we undertook ex situ experiments comparing bryozoan larval settlement to determine if introduced species demonstrate a greater propensity to settle as epibionts, and a reduced propensity to be basibionts, than native species. Here we report that introduced species opportunistically settle on any space (bare, native, or introduced), whereas native species exhibit a strong tendency to settle on and near other natives, but avoid settling on or near introduced basibionts. In addition, larvae of native species experience greater larval wastage (mortality) than introduced species, both in the presence and absence of living substrates. Introduced species’ ability to settle on natives as epibionts, and in turn avoid epibiosis as basibionts, combined with significantly enhanced native larval wastage, provides a comprehensive suite of competitive advantages contributing to the invasion success of these biofouling species.

text: Epibiotic pressure contributes to biofouling invader success Reduced competition is a frequent explanation for the success of many introduced species. In benthic marine biofouling communities, space limitation leads to high rates of overgrowth competition. Some species can utilise other living organisms as substrate (epibiosis), proffering a competitive advantage for the epibiont. Additionally, some species can prevent or reduce epibiotic settlement on their surfaces and avoid being basibionts. To test whether epibiotic pressure differs between native and introduced species, we undertook ex situ experiments comparing bryozoan larval settlement to determine if introduced species demonstrate a greater propensity to settle as epibionts, and a reduced propensity to be basibionts, than native species. Here we report that introduced species opportunistically settle on any space (bare, native, or introduced), whereas native species exhibit a strong tendency to settle on and near other natives, but avoid settling on or near introduced basibionts. In addition, larvae of native species experience greater larval wastage (mortality) than introduced species, both in the presence and absence of living substrates. Introduced species’ ability to settle on natives as epibionts, and in turn avoid epibiosis as basibionts, combined with significantly enhanced native larval wastage, provides a comprehensive suite of competitive advantages contributing to the invasion success of these biofouling species.

year: 2017

title: Kimihia, rangahaua ngā tikanga heke iho. He taonga huahua e riro mai: Exploring whakapapa as a tool towards a kaupapa Māori assessment framework in early childhood education

authors: Paki, Vanessa Anne

subjects: kaupapa Maori assessment

abstract: This study explores whakapapa as a tool, which can be used as a kaupapa Māori assessment framework in early childhood education, positioning kaupapa Māori theory as a paradigm base underpinning a philosophical and theoretical discourse towards assessment for children's learning. This thesis represents the culmination of a personal and professional journey, derived from the writer's longstanding interest in and commitment to kaupapa Māori early childhood education, and more specifically, philosophies and practices for assessment in this context. The study has canvassed a vast terrain of kaupapa Māori philosophy in its search for a theoretical grounding for a kaupapa Māori assessment framework for early childhood education.
Foundation to the study has been the premise that the notion of whakapapa serves as an overarching philosophical matrix, encompassing the interconnected realms of genealogy, spirituality, and knowledge that precede, surround, and embrace the Māori child. Throughout the thesis, diagrams are employed to demonstrate and model the whakapapa underpinning the conceptualisations being explored. After contextualising the study within a historical overview of the impact of colonisation of kaupapa Māori education and research, it is suggested that a re-examination of key concepts from tikanga Māori will illuminate transformative possibilities applicable to the study's focus on the development of a theoretical base for an assessment tool within kaupapa Māori early childhood settings. Drawing from the literature, the thesis re-positions the view of the Māori child to one of being nurtured within a philosophical construct underpinned and immersed in tikanga such as whakapapa, ira tangata, whanaungatanga, mana and tapu, and ako, providing a strongly Māori theoretical base for the envisioning of the assessment process. The outcome of this study is to propose an assessment framework, which embodies and reflects these core kaupapa Māori philosophies as praxis.

text: Kimihia, rangahaua ngā tikanga heke iho. He taonga huahua e riro mai: Exploring whakapapa as a tool towards a kaupapa Māori assessment framework in early childhood education This study explores whakapapa as a tool, which can be used as a kaupapa Māori assessment framework in early childhood education, positioning kaupapa Māori theory as a paradigm base underpinning a philosophical and theoretical discourse towards assessment for children's learning. This thesis represents the culmination of a personal and professional journey, derived from the writer's longstanding interest in and commitment to kaupapa Māori early childhood education, and more specifically, philosophies and practices for assessment in this context. The study has canvassed a vast terrain of kaupapa Māori philosophy in its search for a theoretical grounding for a kaupapa Māori assessment framework for early childhood education.
Foundation to the study has been the premise that the notion of whakapapa serves as an overarching philosophical matrix, encompassing the interconnected realms of genealogy, spirituality, and knowledge that precede, surround, and embrace the Māori child. Throughout the thesis, diagrams are employed to demonstrate and model the whakapapa underpinning the conceptualisations being explored. After contextualising the study within a historical overview of the impact of colonisation of kaupapa Māori education and research, it is suggested that a re-examination of key concepts from tikanga Māori will illuminate transformative possibilities applicable to the study's focus on the development of a theoretical base for an assessment tool within kaupapa Māori early childhood settings. Drawing from the literature, the thesis re-positions the view of the Māori child to one of being nurtured within a philosophical construct underpinned and immersed in tikanga such as whakapapa, ira tangata, whanaungatanga, mana and tapu, and ako, providing a strongly Māori theoretical base for the envisioning of the assessment process. The outcome of this study is to propose an assessment framework, which embodies and reflects these core kaupapa Māori philosophies as praxis.

year: 2007