title: Ensemble learning of high dimension datasets

authors: Lim, Nick Jin Sean

subjects: Ensemble learning

abstract: Ensemble learning, an approach in Machine Learning, makes decisions based on the collective decision of a committee of learners to solve complex tasks with minimal human intervention. Advances in computing technology have enabled researchers build datasets with the number of features in the order of thousands and enabled building more accurate predictive models. Unfortunately, high dimensional datasets are especially challenging for machine learning due to the phenomenon dubbed as the "curse of dimensionality". One approach to overcoming this challenge is ensemble learning using Random Subspace (RS) method, which has been shown to perform very well empirically however with few theoretical explanations to said effectiveness for classification tasks.

In this thesis, we aim to provide theoretical insights into RS ensemble classifiers to give a more in-depth understanding of the theoretical foundations of other ensemble classifiers. We investigate the conditions for norm-preservations in RS projections. Insights into this provide us with the theoretical basis for RS in algorithms that are based on the geometry of the data (i.e. clustering, nearest-neighbour). We then investigate the guarantees for the dot products of two random vectors after RS projection. This guarantee is useful to capture the geometric structure of a classification problem. We will then investigate the accuracy of a majority vote ensemble using a generalized Polya-Urn model, and how the parameters of the model are derived from diversity measures. We will discuss the practical implications of the model, explore the noise tolerance of ensembles, and give a plausible explanation for the effectiveness of ensembles.

We will provide empirical corroboration for our main results with both synthetic and real-world high-dimensional data. We will also discuss the implications of our theory on other applications (i.e. compressive sensing). Based on our results, we will propose a method of building ensembles for Deep Neural Network image classifications using RS projections without needing to retrain the neural network, which showed improved accuracy and very good robustness to adversarial examples. Ultimately, we hope that the insights gained in this thesis would make in-roads towards the answer to a key open question for ensemble classifiers, "When will an ensemble of weak learners outperform a single carefully tuned learner?"

text: Ensemble learning of high dimension datasets Ensemble learning, an approach in Machine Learning, makes decisions based on the collective decision of a committee of learners to solve complex tasks with minimal human intervention. Advances in computing technology have enabled researchers build datasets with the number of features in the order of thousands and enabled building more accurate predictive models. Unfortunately, high dimensional datasets are especially challenging for machine learning due to the phenomenon dubbed as the "curse of dimensionality". One approach to overcoming this challenge is ensemble learning using Random Subspace (RS) method, which has been shown to perform very well empirically however with few theoretical explanations to said effectiveness for classification tasks.

In this thesis, we aim to provide theoretical insights into RS ensemble classifiers to give a more in-depth understanding of the theoretical foundations of other ensemble classifiers. We investigate the conditions for norm-preservations in RS projections. Insights into this provide us with the theoretical basis for RS in algorithms that are based on the geometry of the data (i.e. clustering, nearest-neighbour). We then investigate the guarantees for the dot products of two random vectors after RS projection. This guarantee is useful to capture the geometric structure of a classification problem. We will then investigate the accuracy of a majority vote ensemble using a generalized Polya-Urn model, and how the parameters of the model are derived from diversity measures. We will discuss the practical implications of the model, explore the noise tolerance of ensembles, and give a plausible explanation for the effectiveness of ensembles.

We will provide empirical corroboration for our main results with both synthetic and real-world high-dimensional data. We will also discuss the implications of our theory on other applications (i.e. compressive sensing). Based on our results, we will propose a method of building ensembles for Deep Neural Network image classifications using RS projections without needing to retrain the neural network, which showed improved accuracy and very good robustness to adversarial examples. Ultimately, we hope that the insights gained in this thesis would make in-roads towards the answer to a key open question for ensemble classifiers, "When will an ensemble of weak learners outperform a single carefully tuned learner?"

year: 2020

title: Formative assessment in science classrooms

authors: Cowie, Bronwen

abstract: This study investigated how formative assessment was perceived, experienced and accomplished by teachers and students in ten Year 7 to 10 science classrooms. The study was undertaken within and built on the findings of the Learning in Science Project (Assessment). An interpretive methodology using interviews and participant observation was employed. The study consisted of two phases. During the first phase, the teachers and at least three students of each teacher were interviewed and three classroom observations undertaken to ascertain views of formative assessment. In phase 2, case studies were developed of the formative assessment in the different classrooms. In addition, the teachers participated in eleven teacher development days, which were audio-taped and analysed. 

While the literature provided a definition and discussion of formative assessment relatively little research had explored student perceptions and experiences of formative assessment as an aspect of their everyday classroom life. The links between formative assessment and views of learning had received very little attention. The study provides empirical evidence that formative assessment is accomplished through situated teacher and student actions and interactions that involve the exchange, interpretation and action on information about student learning. It seems teachers and students are active and intentional participants in the process of formative assessment but not necessarily for the same purposes. Student perceptions that interactions could enhance their learning and harm their relationships with others and their view of themselves led them to consider both the possible benefit and the potential harm of disclosing their ideas to others (teachers and peers). Moreover, students indicated that whether they pursued learning or performance goals and how they perceived teacher assessment purposes influenced their purposes for and willingness to participate in assessment interactions. Cognition, affect, conation and relationships with others were experienced by the students as inextricably intertwined with their learning and the formative assessment of it. Thus, the findings indicate that formative assessment contributes to the meaning of being a student, learner, knower and peer and of being a teacher in the classroom.

The findings of the study support the view that formative assessment is a sociocultural activity that may be described and is accomplished along three interdependent planes of the classroom, interpersonal and personal activity and meaning (Rogoff, 1995). On the classroom plane, formative assessment is accomplished through a process of apprenticeship and influences what it means to be a student (and a teacher). On the interpersonal plane, formative assessment is accomplished through a process of guided participation and influences what is taken and counts as school science and hence what it means to be a student (of science) in a particular classroom. It shapes how students view themselves and each other in the social milieu of the classroom. On the personal plane it shapes the language students use and how they feel about themselves as learners and knowers of school science.

text: Formative assessment in science classrooms This study investigated how formative assessment was perceived, experienced and accomplished by teachers and students in ten Year 7 to 10 science classrooms. The study was undertaken within and built on the findings of the Learning in Science Project (Assessment). An interpretive methodology using interviews and participant observation was employed. The study consisted of two phases. During the first phase, the teachers and at least three students of each teacher were interviewed and three classroom observations undertaken to ascertain views of formative assessment. In phase 2, case studies were developed of the formative assessment in the different classrooms. In addition, the teachers participated in eleven teacher development days, which were audio-taped and analysed. 

While the literature provided a definition and discussion of formative assessment relatively little research had explored student perceptions and experiences of formative assessment as an aspect of their everyday classroom life. The links between formative assessment and views of learning had received very little attention. The study provides empirical evidence that formative assessment is accomplished through situated teacher and student actions and interactions that involve the exchange, interpretation and action on information about student learning. It seems teachers and students are active and intentional participants in the process of formative assessment but not necessarily for the same purposes. Student perceptions that interactions could enhance their learning and harm their relationships with others and their view of themselves led them to consider both the possible benefit and the potential harm of disclosing their ideas to others (teachers and peers). Moreover, students indicated that whether they pursued learning or performance goals and how they perceived teacher assessment purposes influenced their purposes for and willingness to participate in assessment interactions. Cognition, affect, conation and relationships with others were experienced by the students as inextricably intertwined with their learning and the formative assessment of it. Thus, the findings indicate that formative assessment contributes to the meaning of being a student, learner, knower and peer and of being a teacher in the classroom.

The findings of the study support the view that formative assessment is a sociocultural activity that may be described and is accomplished along three interdependent planes of the classroom, interpersonal and personal activity and meaning (Rogoff, 1995). On the classroom plane, formative assessment is accomplished through a process of apprenticeship and influences what it means to be a student (and a teacher). On the interpersonal plane, formative assessment is accomplished through a process of guided participation and influences what is taken and counts as school science and hence what it means to be a student (of science) in a particular classroom. It shapes how students view themselves and each other in the social milieu of the classroom. On the personal plane it shapes the language students use and how they feel about themselves as learners and knowers of school science.

year: 2000

title: Educational leadership and Māori communities’ involvement in their children’s schooling

authors: McMillan, Hoana

subjects: Educational leadership

abstract: The leadership of state primary schools in New Zealand is made up of Board of Trustees (BoT) members and the principal who together, play an important role in addressing take Māori – Māori issues, to enable better outcomes for Māori achievement and empowering relationships with Māori communities.  However not all schools have met their professional responsibilities to provide a learning environment that promotes the success of their Māori students (Education Review Office, 2010) therefore an important question for Māori communities to contemplate is whether they need to take up a more active role in ensuring accountability from these parties, as well as actively contributing to efforts to ensure better outcomes for their children.
The case studies presented in this thesis examine two successful mainstream primary schools identified as doing well in terms of Māori achievement and empowering relationships with their Māori communities.  It explores the knowledge of Māori Board of Trustees Members (MBTMS) and also their perceptions of what Māori communities know regarding school leadership and policies and procedures relating to Māori achievement and Māori communities.  It also explores the knowledge of their school leadership in terms of leadership that works well with Māori communities, and how Māori communities might work alongside school leadership effectively.  The case studies were conducted in a kaupapa Māori framework where the collection and analysis of qualitative data included school documents, observations of Boards of Trustees (BoT) meetings, information about professional development relating to Māori achievement and or Māori communities, and semi-structured interviews with the MBTMS and principals.
The literature review highlighted the relationship between the role of principals and their knowledge of Māori perspectives toward meeting outcomes for Māori achievement and empowering relationships with Māori communities. It also highlighted the role of the BoT and the implications of ethnicity and of legislation toward meeting these outcomes.  Lastly it highlighted the evolution of whānau roles within education, and the ability of whānau to challenge school leadership towards meeting these outcomes.
The findings from the case studies indicate that the knowledge of MBTMS with regards to the roles of school leadership and policies and procedures relating to Māori achievement and Māori communities were consistent with the structure of partnerships within their school leadership.  The knowledge of school leadership across the case studies regarding leadership that works well with Māori communities is consistent with traditional whānau roles within education where there is emphasis on the well-being of Māori, creating the following conditions of school culture and climate within their schools – Whakamana Tangata – Acknowledging People, Whakamana Whānau – Acknowledging Family, Whakamana Tikanga, Acknowledging Protocol, Whakamana Reo – Acknowledging Language, Matauranga Māori – Knowledge of Māori worldviews, Pono – Trust, and Manaaki – Care.
The study suggests further research examining what Māori community members, beyond MTBMS, know about the role of school leadership and of policies and procedures relating to Māori achievement and Māori communities, and how Māori communities might envisage working alongside school leadership.  However, this study does offer a useful point of reflection and discussion for school leadership interested in improving their practice toward better outcomes for Māori.

text: Educational leadership and Māori communities’ involvement in their children’s schooling The leadership of state primary schools in New Zealand is made up of Board of Trustees (BoT) members and the principal who together, play an important role in addressing take Māori – Māori issues, to enable better outcomes for Māori achievement and empowering relationships with Māori communities.  However not all schools have met their professional responsibilities to provide a learning environment that promotes the success of their Māori students (Education Review Office, 2010) therefore an important question for Māori communities to contemplate is whether they need to take up a more active role in ensuring accountability from these parties, as well as actively contributing to efforts to ensure better outcomes for their children.
The case studies presented in this thesis examine two successful mainstream primary schools identified as doing well in terms of Māori achievement and empowering relationships with their Māori communities.  It explores the knowledge of Māori Board of Trustees Members (MBTMS) and also their perceptions of what Māori communities know regarding school leadership and policies and procedures relating to Māori achievement and Māori communities.  It also explores the knowledge of their school leadership in terms of leadership that works well with Māori communities, and how Māori communities might work alongside school leadership effectively.  The case studies were conducted in a kaupapa Māori framework where the collection and analysis of qualitative data included school documents, observations of Boards of Trustees (BoT) meetings, information about professional development relating to Māori achievement and or Māori communities, and semi-structured interviews with the MBTMS and principals.
The literature review highlighted the relationship between the role of principals and their knowledge of Māori perspectives toward meeting outcomes for Māori achievement and empowering relationships with Māori communities. It also highlighted the role of the BoT and the implications of ethnicity and of legislation toward meeting these outcomes.  Lastly it highlighted the evolution of whānau roles within education, and the ability of whānau to challenge school leadership towards meeting these outcomes.
The findings from the case studies indicate that the knowledge of MBTMS with regards to the roles of school leadership and policies and procedures relating to Māori achievement and Māori communities were consistent with the structure of partnerships within their school leadership.  The knowledge of school leadership across the case studies regarding leadership that works well with Māori communities is consistent with traditional whānau roles within education where there is emphasis on the well-being of Māori, creating the following conditions of school culture and climate within their schools – Whakamana Tangata – Acknowledging People, Whakamana Whānau – Acknowledging Family, Whakamana Tikanga, Acknowledging Protocol, Whakamana Reo – Acknowledging Language, Matauranga Māori – Knowledge of Māori worldviews, Pono – Trust, and Manaaki – Care.
The study suggests further research examining what Māori community members, beyond MTBMS, know about the role of school leadership and of policies and procedures relating to Māori achievement and Māori communities, and how Māori communities might envisage working alongside school leadership.  However, this study does offer a useful point of reflection and discussion for school leadership interested in improving their practice toward better outcomes for Māori.

year: 2012