title: Practical bias variance decomposition

authors: Bouckaert, Remco R.

subjects: computer science

abstract: Bias variance decomposition for classifiers is a useful tool in understanding classifier behavior. Unfortunately, the literature does not provide consistent guidelines on how to apply a bias variance decomposition. This paper examines the various parameters and variants of empirical bias variance decompositions through an extensive simulation study. Based on this study, we recommend to use ten fold cross validation as sampling method and take 100 samples within each fold with a test set size of at least 2000. Only if the learning algorithm is stable, fewer samples, a smaller test set size or lower number of folds may be justified.

text: Practical bias variance decomposition Bias variance decomposition for classifiers is a useful tool in understanding classifier behavior. Unfortunately, the literature does not provide consistent guidelines on how to apply a bias variance decomposition. This paper examines the various parameters and variants of empirical bias variance decompositions through an extensive simulation study. Based on this study, we recommend to use ten fold cross validation as sampling method and take 100 samples within each fold with a test set size of at least 2000. Only if the learning algorithm is stable, fewer samples, a smaller test set size or lower number of folds may be justified.

year: 2008

title: Developing a survey instrument to evaluate tertiary chemistry students' attitudes and learning experiences

authors: Coll, Richard K.

abstract: New Zealand tertiary institutions, like others worldwide, have experienced a decline in science and chemistry enrolments in recent times as students seek other career paths that they perceive to be more lucrative. In a previous article we described a qualitative study of the learning experiences of students enrolled in a first year chemistry course at a New Zealand tertiary institution. Researchers in education and science education have two choices of methodology, a qualitative or a quantitative approach, and each possesses advantages and disadvantages. Qualitative studies typically use resource intensive data gathering techniques such as interviews. These studies are useful in that they allow researchers to study issues of interest in great depth and, for example, allow investigators to probe for underlying reasons about students' views for abstract scientific concepts. However, because qualitative studies are more labour intensive, they typically involve only small numbers of participants, which in the minds of many researchers and teachers results in a lack of generalisability. In other words, it is not necessarily clear what implications the findings hold in other contexts. In contrast, quantitative studies involve larger numbers of participants. By the judicious use of statistical analysis, researchers can investigate changes and trends, and extrapolate their findings to a large (or target) population. However, whilst the results from quantitative studies are more generalisable, they are often less detailed. Hence researchers are confronted with a trade-off situation in which they must choose between the depth of understanding provided from qualitative studies, versus the generalisability of a quantitative approach: because of this dilemma, increasingly researchers employ a mixed methodology approach. In this paper we describe a quantitative study that complements previous qualitative work. We report on the development of a questionnaire that investigates tertiary level learning experiences of chemistry students, along with their attitude toward chemistry and chemistry self-efficacy.

text: Developing a survey instrument to evaluate tertiary chemistry students' attitudes and learning experiences New Zealand tertiary institutions, like others worldwide, have experienced a decline in science and chemistry enrolments in recent times as students seek other career paths that they perceive to be more lucrative. In a previous article we described a qualitative study of the learning experiences of students enrolled in a first year chemistry course at a New Zealand tertiary institution. Researchers in education and science education have two choices of methodology, a qualitative or a quantitative approach, and each possesses advantages and disadvantages. Qualitative studies typically use resource intensive data gathering techniques such as interviews. These studies are useful in that they allow researchers to study issues of interest in great depth and, for example, allow investigators to probe for underlying reasons about students' views for abstract scientific concepts. However, because qualitative studies are more labour intensive, they typically involve only small numbers of participants, which in the minds of many researchers and teachers results in a lack of generalisability. In other words, it is not necessarily clear what implications the findings hold in other contexts. In contrast, quantitative studies involve larger numbers of participants. By the judicious use of statistical analysis, researchers can investigate changes and trends, and extrapolate their findings to a large (or target) population. However, whilst the results from quantitative studies are more generalisable, they are often less detailed. Hence researchers are confronted with a trade-off situation in which they must choose between the depth of understanding provided from qualitative studies, versus the generalisability of a quantitative approach: because of this dilemma, increasingly researchers employ a mixed methodology approach. In this paper we describe a quantitative study that complements previous qualitative work. We report on the development of a questionnaire that investigates tertiary level learning experiences of chemistry students, along with their attitude toward chemistry and chemistry self-efficacy.

year: 2001

title: Donna Awatere’s Māori Sovereignty: Reflections on White Supremacy and the Racialization of Crime Control and Surveillance in Aotearoa New Zealand

authors: Dawson, Brian

abstract: Donna Awatere’s examination of whiteness within the Aotearoa New Zealand context, specifically white cultural imperialism, has largely been ignored in academic scholarship. For her, white culture, and its articulation through governance and policy, is the starting point and lens to understanding and addressing historical and contemporary Māori dispossession and ensuing strategies of racialized surveillance, control, and containment. In this essay, we argue that Awatere’s attention to past forms of genocide – mapping them to emerging forms of state confinement of Māori, which engender genocidal characteristics, and problematizing “whiteness” – situates the book Māori Sovereignty as an important text in the field of criminal justice, especially that which manifests in settler-colonial contexts.

text: Donna Awatere’s Māori Sovereignty: Reflections on White Supremacy and the Racialization of Crime Control and Surveillance in Aotearoa New Zealand Donna Awatere’s examination of whiteness within the Aotearoa New Zealand context, specifically white cultural imperialism, has largely been ignored in academic scholarship. For her, white culture, and its articulation through governance and policy, is the starting point and lens to understanding and addressing historical and contemporary Māori dispossession and ensuing strategies of racialized surveillance, control, and containment. In this essay, we argue that Awatere’s attention to past forms of genocide – mapping them to emerging forms of state confinement of Māori, which engender genocidal characteristics, and problematizing “whiteness” – situates the book Māori Sovereignty as an important text in the field of criminal justice, especially that which manifests in settler-colonial contexts.

year: 2023-07-27