title: Tree-structured multiclass probability estimators

authors: Leathart, Timothy Matthew

abstract: Nested dichotomies are used as a method of transforming a multiclass classification problem into a series of binary problems. A binary tree structure is constructed over the label space that recursively splits the set of classes into subsets, and a binary classification model learns to discriminate between the two subsets of classes at each node. Several distinct nested dichotomy structures can be built in an ensemble for superior performance. In this thesis, we introduce two new methods for constructing more accurate nested dichotomies. Random-pair selection is a subset selection method that aims to group similar classes together in a non-deterministic fashion to easily enable the construction of accurate ensembles. Multiple subset evaluation takes this, and other subset selection methods, further by evaluating several different splits and choosing the best performing one. Finally, we also discuss the calibration of the probability estimates produced by nested dichotomies. We observe that nested dichotomies systematically produce under-confident predictions, even if the binary classifiers are well calibrated, and especially when the number of classes is high. Furthermore, substantial performance gains can be made when probability calibration methods are also applied to the internal models.

text: Tree-structured multiclass probability estimators Nested dichotomies are used as a method of transforming a multiclass classification problem into a series of binary problems. A binary tree structure is constructed over the label space that recursively splits the set of classes into subsets, and a binary classification model learns to discriminate between the two subsets of classes at each node. Several distinct nested dichotomy structures can be built in an ensemble for superior performance. In this thesis, we introduce two new methods for constructing more accurate nested dichotomies. Random-pair selection is a subset selection method that aims to group similar classes together in a non-deterministic fashion to easily enable the construction of accurate ensembles. Multiple subset evaluation takes this, and other subset selection methods, further by evaluating several different splits and choosing the best performing one. Finally, we also discuss the calibration of the probability estimates produced by nested dichotomies. We observe that nested dichotomies systematically produce under-confident predictions, even if the binary classifiers are well calibrated, and especially when the number of classes is high. Furthermore, substantial performance gains can be made when probability calibration methods are also applied to the internal models.

year: 2019

title: Book review: The politics of language education: Individuals and institutions.

authors: Barnard, Roger

subjects: book review

abstract: This article reviews the book: “The politics of language education: Individuals and institutions”, edited by J.C. Alderson.

text: Book review: The politics of language education: Individuals and institutions. This article reviews the book: “The politics of language education: Individuals and institutions”, edited by J.C. Alderson.

year: 2010

title: The Control, environmental sustainability and information management of Maori land in New Zealand

authors: Morad, Munir

subjects: Maori land

abstract: An increase in Maori land claims and the subsequent settlement of a number of land confiscation grievances have prompted calls for change to the land management, cadastral and legal regimes in New Zealand. There is little expert agreement as to Me shape any such reforms should take, but environmental planners and Maori leaders have conceded the need for an overhaul of current land information management practices. Such reforms must aspire to being legally workable, culturally appropriate and environmentally sustainable.
Most land in New Zealand is subject to recent legislation (post-1984) which acknowledges concern for Maori cultural values and ancestral rights and environmental sustainability. The existence of this legislation and growing Maori involvement in formulating public policy for the management of land and environmental resources mean that Maori concepts of land management and sustainability are receiving increasing attention and are likely to influence the shape of future cadastral reforms for Maori lands.

text: The Control, environmental sustainability and information management of Maori land in New Zealand An increase in Maori land claims and the subsequent settlement of a number of land confiscation grievances have prompted calls for change to the land management, cadastral and legal regimes in New Zealand. There is little expert agreement as to Me shape any such reforms should take, but environmental planners and Maori leaders have conceded the need for an overhaul of current land information management practices. Such reforms must aspire to being legally workable, culturally appropriate and environmentally sustainable.
Most land in New Zealand is subject to recent legislation (post-1984) which acknowledges concern for Maori cultural values and ancestral rights and environmental sustainability. The existence of this legislation and growing Maori involvement in formulating public policy for the management of land and environmental resources mean that Maori concepts of land management and sustainability are receiving increasing attention and are likely to influence the shape of future cadastral reforms for Maori lands.

year: 1997