title: Pruning decision trees and lists

authors: Frank, Eibe

abstract: Machine learning algorithms are techniques that automatically build models describing the structure at the heart of a set of data. Ideally, such models can be used to predict properties of future data points and people can use them to analyze the domain from which the data originates. 

Decision trees and lists are potentially powerful predictors and embody an explicit representation of the structure in a dataset. Their accuracy and comprehensibility depends on how concisely the learning algorithm can summarize this structure. The final model should not incorporate spurious effects-patterns that are not genuine features of the underlying domain. Given an efficient mechanism for determining when a particular effect is due to chance alone, non-predictive parts of a model can be eliminated or “pruned.” Pruning mechanisms require a sensitive instrument that uses the data to detect whether there is a genuine relationship between the components of a model and the domain. Statistical significance tests are theoretically well-founded tools for doing exactly that. 

This thesis presents pruning algorithms for decision trees and lists that are based on significance tests. We explain why pruning is often necessary to obtain small and accurate models and show that the performance of standard pruning algorithms can be improved by taking the statistical significance of observations into account. We compare the effect of parametric and non-parametric tests, analyze why current pruning algorithms for decision lists often prune too aggressively, and review related work-in particular existing approaches that use significance tests in the context of pruning. The main outcome of this investigation is a set of simple pruning algorithms that should prove useful in practical data mining applications.

text: Pruning decision trees and lists Machine learning algorithms are techniques that automatically build models describing the structure at the heart of a set of data. Ideally, such models can be used to predict properties of future data points and people can use them to analyze the domain from which the data originates. 

Decision trees and lists are potentially powerful predictors and embody an explicit representation of the structure in a dataset. Their accuracy and comprehensibility depends on how concisely the learning algorithm can summarize this structure. The final model should not incorporate spurious effects-patterns that are not genuine features of the underlying domain. Given an efficient mechanism for determining when a particular effect is due to chance alone, non-predictive parts of a model can be eliminated or “pruned.” Pruning mechanisms require a sensitive instrument that uses the data to detect whether there is a genuine relationship between the components of a model and the domain. Statistical significance tests are theoretically well-founded tools for doing exactly that. 

This thesis presents pruning algorithms for decision trees and lists that are based on significance tests. We explain why pruning is often necessary to obtain small and accurate models and show that the performance of standard pruning algorithms can be improved by taking the statistical significance of observations into account. We compare the effect of parametric and non-parametric tests, analyze why current pruning algorithms for decision lists often prune too aggressively, and review related work-in particular existing approaches that use significance tests in the context of pruning. The main outcome of this investigation is a set of simple pruning algorithms that should prove useful in practical data mining applications.

year: 2000

title: Designing a mobile augmented memory system for people with traumatic brain injuries

authors: Chang, Carole

subjects: computer system

abstract: Augmented memory systems help people remember events in their lives. Individuals with Traumatic Brain Injury (TBI) often have memory impairments. We conducted a user study to learn about strategies individuals with TBI use to remember events in their lives. We explored what characteristics individuals with TBI expect of an augmented memory system. We then investigated these aspects in an initial mobile app design, and propose here a concept for a rehearsal application that addresses the issues found in our studies.

text: Designing a mobile augmented memory system for people with traumatic brain injuries Augmented memory systems help people remember events in their lives. Individuals with Traumatic Brain Injury (TBI) often have memory impairments. We conducted a user study to learn about strategies individuals with TBI use to remember events in their lives. We explored what characteristics individuals with TBI expect of an augmented memory system. We then investigated these aspects in an initial mobile app design, and propose here a concept for a rehearsal application that addresses the issues found in our studies.

year: 2014

title: Toi Tuku Iho: An exploration of oranga and mana motuhake through toi

authors: Waititi, Kahurangi Rora

subjects: Toi tuku iho

abstract: This research examines how mahi toi as process, theory, and output can contribute to oranga and mana motuhake for whānau, hapū, and iwi which is explored through the tribal storytelling practices of Te Whānau a Apanui. In this thesis, I argue that kōrero tuku iho is the umbilical link to our ancestors that sustains us with teachings; cultivating a richness and depth of self and connection through story. I demonstrate that the vehicles of sharing are as varied as the stories themselves and are known as “toi” or our creative expressions of kōrero tuku iho. 
The key focus of this thesis is to reveal how toi can be used to decolonise and re-indigenise research methodologies and facilitate transformation through praxis. Iwi storytellers were interviewed, sharing that within our toi practices lie a myriad of ways to challenge colonial structures and ideologies, ground us in tīpuna knowledge systems, and provide a space to innovate solutions to the challenges of te ao hurihuri (a changing world). The kaikōrero provided a collective and relational lens that fostered the development of a Toi Tuku Iho methodology. This was processed through a creative output that I created of a digital story that was filmed to reveal how knowledge through stories can become taonga tuku iho. A Toi Tuku Iho methodology is proffered to understand the complex processes of iwi storytelling and reveal the relationality between innovation and what this thesis refers to as the tipuna continuum.
Themes explored in the thesis are an ecosystem of learning through people, place, story, whakapapa and time; how iwi oranga is viewed and contributed to by toi; and how mana motuhake is embraced and enacted through kōrero tuku iho. Furthermore, the application of kaupapa Māori creative practices to this research expands the academic confines of knowledge production to include Indigenous stories and toi. The thesis demonstrates that the research process, potential products, and outcomes, are transformed by using these practices.  Storyscapes, timescapes, landscapes and generations past and future merge together, in this research, to facilitate dreams and aspirations for future generations. The collapsing of timescapes is explored through audio-visual digital storytelling, a medium known to manoeuvre time to enhance a story. I seek to amplify the power of tribal storytelling through toi to transform the spaces we occupy both within and outside of our iwi. Mahi toi ignites our creative selves to dream and can activate a belief to explore beyond what we know. I argue that Toi Tuku Iho has the potential to engage communities, on their own terms, in their own ways and for their own means.

text: Toi Tuku Iho: An exploration of oranga and mana motuhake through toi This research examines how mahi toi as process, theory, and output can contribute to oranga and mana motuhake for whānau, hapū, and iwi which is explored through the tribal storytelling practices of Te Whānau a Apanui. In this thesis, I argue that kōrero tuku iho is the umbilical link to our ancestors that sustains us with teachings; cultivating a richness and depth of self and connection through story. I demonstrate that the vehicles of sharing are as varied as the stories themselves and are known as “toi” or our creative expressions of kōrero tuku iho. 
The key focus of this thesis is to reveal how toi can be used to decolonise and re-indigenise research methodologies and facilitate transformation through praxis. Iwi storytellers were interviewed, sharing that within our toi practices lie a myriad of ways to challenge colonial structures and ideologies, ground us in tīpuna knowledge systems, and provide a space to innovate solutions to the challenges of te ao hurihuri (a changing world). The kaikōrero provided a collective and relational lens that fostered the development of a Toi Tuku Iho methodology. This was processed through a creative output that I created of a digital story that was filmed to reveal how knowledge through stories can become taonga tuku iho. A Toi Tuku Iho methodology is proffered to understand the complex processes of iwi storytelling and reveal the relationality between innovation and what this thesis refers to as the tipuna continuum.
Themes explored in the thesis are an ecosystem of learning through people, place, story, whakapapa and time; how iwi oranga is viewed and contributed to by toi; and how mana motuhake is embraced and enacted through kōrero tuku iho. Furthermore, the application of kaupapa Māori creative practices to this research expands the academic confines of knowledge production to include Indigenous stories and toi. The thesis demonstrates that the research process, potential products, and outcomes, are transformed by using these practices.  Storyscapes, timescapes, landscapes and generations past and future merge together, in this research, to facilitate dreams and aspirations for future generations. The collapsing of timescapes is explored through audio-visual digital storytelling, a medium known to manoeuvre time to enhance a story. I seek to amplify the power of tribal storytelling through toi to transform the spaces we occupy both within and outside of our iwi. Mahi toi ignites our creative selves to dream and can activate a belief to explore beyond what we know. I argue that Toi Tuku Iho has the potential to engage communities, on their own terms, in their own ways and for their own means.

year: 2023