title: Naïve Bayes for text classification with unbalanced classes

authors: Frank, Eibe

subjects: computer science

abstract: Multinomial naive Bayes (MNB) is a popular method for document classification due to its computational efficiency and relatively good predictive performance. It has recently been established that predictive performance can be improved further by appropriate data transformations [1,2]. In this paper we present another transformation that is designed to combat a potential problem with the application of MNB to unbalanced datasets. We propose an appropriate correction by adjusting attribute priors. This correction can be implemented as another data normalization step, and we show that it can significantly improve the area under the ROC curve. We also show that the modified version of MNB is very closely related to the simple centroid-based classifier and compare the two methods empirically.

text: Naïve Bayes for text classification with unbalanced classes Multinomial naive Bayes (MNB) is a popular method for document classification due to its computational efficiency and relatively good predictive performance. It has recently been established that predictive performance can be improved further by appropriate data transformations [1,2]. In this paper we present another transformation that is designed to combat a potential problem with the application of MNB to unbalanced datasets. We propose an appropriate correction by adjusting attribute priors. This correction can be implemented as another data normalization step, and we show that it can significantly improve the area under the ROC curve. We also show that the modified version of MNB is very closely related to the simple centroid-based classifier and compare the two methods empirically.

year: 2006

title: Puarenga Stream alum dosing – effects on Lake Rotorua/Sulphur Bay biota 2016

authors: Ling, Nicholas

abstract: Continuous alum dosing of the Puarenga Stream commenced in early 2010 to reduce inflows of dissolved reactive phosphorus to Lake Rotorua. Analyses of bioaccumulation in the tissues of macrobiota were undertaken in February 2016 for comparison to comparable samples obtained prior to and since the commencement of alum dosing to satisfy annual resource consent conditions 8.7 and 8.8 of resource consent 65559.

No significant effects of alum dosing could be distinguished. Bioavailable aluminium in the vicinity of Sulphur Bay appears to be primarily influenced by the major geothermal activity of this region. Lake water chemistry in the vicinity of Sulphur Bay is heavily influenced by the direction of geothermal flows emanating from the Bay. No significant differences in aluminium bioaccumulation were observed in any species compared to samples obtained prior to the commencement of alum dosing. Continuous alum dosing of the Puarenga Stream since 2010 apparently does not result in adverse effects to Lake Rotorua shoreline biota nor cause any apparent increase in aluminium bioaccumulation in lake biota in the vicinity of Sulphur Bay.

text: Puarenga Stream alum dosing – effects on Lake Rotorua/Sulphur Bay biota 2016 Continuous alum dosing of the Puarenga Stream commenced in early 2010 to reduce inflows of dissolved reactive phosphorus to Lake Rotorua. Analyses of bioaccumulation in the tissues of macrobiota were undertaken in February 2016 for comparison to comparable samples obtained prior to and since the commencement of alum dosing to satisfy annual resource consent conditions 8.7 and 8.8 of resource consent 65559.

No significant effects of alum dosing could be distinguished. Bioavailable aluminium in the vicinity of Sulphur Bay appears to be primarily influenced by the major geothermal activity of this region. Lake water chemistry in the vicinity of Sulphur Bay is heavily influenced by the direction of geothermal flows emanating from the Bay. No significant differences in aluminium bioaccumulation were observed in any species compared to samples obtained prior to the commencement of alum dosing. Continuous alum dosing of the Puarenga Stream since 2010 apparently does not result in adverse effects to Lake Rotorua shoreline biota nor cause any apparent increase in aluminium bioaccumulation in lake biota in the vicinity of Sulphur Bay.

year: 2017

title: Processes of Pakeha change in response to the Treaty of Waitangi

authors: Huygens, Ingrid Louise Maria

subjects: Pakeha change

abstract: The sense of crisis that marks our times may be seen as a crisis for dominant groups whose once-secure hegemony is being challenged by marginalised others. It is in theorising the reply from the dominant group to the voices of the oppressed that existing Western conceptions of social change fall silent. The dominant Pakeha group in Aotearoa New Zealand has used discourses of benign colonisation and harmonious race relations to resist 165 years of communication from indigenous Māori about their oppression and a dishonoured treaty for settlement. My research documents the appearance of the Treaty of Waitangi into the Pakeha consciousness, and the now 30 year-long response by a Pakeha antiracism movement to educate their own cultural group about its agreements. Targeting government, community and social services organisations, activist educators used Freire's (1975) approach of conscientising dialogue to present a more critical view of colonisation, and to encourage participants to consider the complicity of their organisations in ongoing structural and cultural racism.

Based on my membership of local and national networks of activist educators, I was able to organise and facilitate data gathering from three sources to investigate processes of Pakeha change in: (i) unpublished material describing the antiracism and Treaty movement's historical theorising and strategies over 30 years, (ii) a country-wide process of co-theorising among contemporary Treaty educator groups about their work and perceived influence, and (iii) a collection of organisational accounts of Treaty-focused change. The collected records confirmed that a coherent anti-colonial discourse, which I have termed 'Pakeha honouring the Treaty', was in use to construct institutional and constitutional changes in non-government organisations. My interpretation of key elements in a local theory of transforming action included emotional responses to counter-cultural information, collective work for cultural and institutional change and practising a mutually agreed relationship with Māori. I concluded that these emotional, collective and relationship processes in dominant group change were crucial in helping to construct the new conceptual resources of 'affirming Māori authority' and 'striving towards a right relationship with Māori'. These counter-colonial constructions allowed Pakeha a non-resistant and facilitative response to Māori challenge, and enabled a dialogue with Māori about decolonisation. 

By examining in one research programme the genealogy and interdependencies of a new discourse, my research contributes to theorising about the production of new, counter-hegemonic discourses, and confirms the crucial part played by social movements in developing new, liberatory constructions of the social order.

My research calls for further theory-building on (i) emotional and spiritual aspects of transformational learning, (ii) processes involved in consciously-undertaken cultural change by dominant/coloniser groups, and (iii) practising of mutually agreed relationships with indigenous peoples by dominant/coloniser groups. 

My research has implications for theorising how coloniser and dominant groups generally may participate in liberatory social change and decolonisation work, and  the part played by the Western states in the global struggles by indigenous people for recognition of their world-views and aspirations.  

It remains to be seen whether counter-colonial discourses and organisational changes aimed at 'honouring the Treaty' with indigenous peoples will be sufficiently widely adopted to help transform Western dominating cultures and colonial projects. In the meantime, acknowledging and documenting these counter-colonial discourses and their constructions opens up increasing possibilities for constructing, from a history of colonisation, a different future.

text: Processes of Pakeha change in response to the Treaty of Waitangi The sense of crisis that marks our times may be seen as a crisis for dominant groups whose once-secure hegemony is being challenged by marginalised others. It is in theorising the reply from the dominant group to the voices of the oppressed that existing Western conceptions of social change fall silent. The dominant Pakeha group in Aotearoa New Zealand has used discourses of benign colonisation and harmonious race relations to resist 165 years of communication from indigenous Māori about their oppression and a dishonoured treaty for settlement. My research documents the appearance of the Treaty of Waitangi into the Pakeha consciousness, and the now 30 year-long response by a Pakeha antiracism movement to educate their own cultural group about its agreements. Targeting government, community and social services organisations, activist educators used Freire's (1975) approach of conscientising dialogue to present a more critical view of colonisation, and to encourage participants to consider the complicity of their organisations in ongoing structural and cultural racism.

Based on my membership of local and national networks of activist educators, I was able to organise and facilitate data gathering from three sources to investigate processes of Pakeha change in: (i) unpublished material describing the antiracism and Treaty movement's historical theorising and strategies over 30 years, (ii) a country-wide process of co-theorising among contemporary Treaty educator groups about their work and perceived influence, and (iii) a collection of organisational accounts of Treaty-focused change. The collected records confirmed that a coherent anti-colonial discourse, which I have termed 'Pakeha honouring the Treaty', was in use to construct institutional and constitutional changes in non-government organisations. My interpretation of key elements in a local theory of transforming action included emotional responses to counter-cultural information, collective work for cultural and institutional change and practising a mutually agreed relationship with Māori. I concluded that these emotional, collective and relationship processes in dominant group change were crucial in helping to construct the new conceptual resources of 'affirming Māori authority' and 'striving towards a right relationship with Māori'. These counter-colonial constructions allowed Pakeha a non-resistant and facilitative response to Māori challenge, and enabled a dialogue with Māori about decolonisation. 

By examining in one research programme the genealogy and interdependencies of a new discourse, my research contributes to theorising about the production of new, counter-hegemonic discourses, and confirms the crucial part played by social movements in developing new, liberatory constructions of the social order.

My research calls for further theory-building on (i) emotional and spiritual aspects of transformational learning, (ii) processes involved in consciously-undertaken cultural change by dominant/coloniser groups, and (iii) practising of mutually agreed relationships with indigenous peoples by dominant/coloniser groups. 

My research has implications for theorising how coloniser and dominant groups generally may participate in liberatory social change and decolonisation work, and  the part played by the Western states in the global struggles by indigenous people for recognition of their world-views and aspirations.  

It remains to be seen whether counter-colonial discourses and organisational changes aimed at 'honouring the Treaty' with indigenous peoples will be sufficiently widely adopted to help transform Western dominating cultures and colonial projects. In the meantime, acknowledging and documenting these counter-colonial discourses and their constructions opens up increasing possibilities for constructing, from a history of colonisation, a different future.

year: 2007