title: An invalidation test for predictive models

authors: Bardsley, W. Earl

subjects: model invalidation

abstract: The standard means of establishing predictive ability in hydrological models is by finding how well predictions match independent validation data. This matching may not be particularly good in some situations such as seasonal flow forecasting and the question arises as to whether a given model has any predictive capacity. A model-independent significance test of the presence of predictive ability is proposed through random permutations of the predicted values. The null hypothesis of no model predictive ability is accepted if there is a sufficiently high probability that a random reordering of the predicted values will yield a better fit to the validation data. The test can achieve significance even with poor model predictions and its value is for invalidating bad models rather than verifying good models as suitable for application. Some preliminary applications suggest that test outcomes will often be similar at the 0.05 level for standard fit measures using absolute or squared residuals. In addition to hydrological application, the test may also find use as a base quality control measure for predictive models generally.

text: An invalidation test for predictive models The standard means of establishing predictive ability in hydrological models is by finding how well predictions match independent validation data. This matching may not be particularly good in some situations such as seasonal flow forecasting and the question arises as to whether a given model has any predictive capacity. A model-independent significance test of the presence of predictive ability is proposed through random permutations of the predicted values. The null hypothesis of no model predictive ability is accepted if there is a sufficiently high probability that a random reordering of the predicted values will yield a better fit to the validation data. The test can achieve significance even with poor model predictions and its value is for invalidating bad models rather than verifying good models as suitable for application. Some preliminary applications suggest that test outcomes will often be similar at the 0.05 level for standard fit measures using absolute or squared residuals. In addition to hydrological application, the test may also find use as a base quality control measure for predictive models generally.

year: 2007

title: Temporal dynamics of microbial communities in geothermal hotsprings of the Taupo Volcanic Zone

authors: Lowe, Caitlin Louise

subjects: microbial

abstract: Few studies of microbial biogeography address temporal variability in physicochemical conditions and communities in geothermal environments. Here we examine the temporal variability of 43 chemical analytes, temperature and pH in association with microbial community composition of 69 water samples collected bimonthly from 12 hotsprings of the Taupo Volcanic Zone between December 2015 and October 2016. Communities and physicochemical parameters were characterized using a combination of next generation Ion Torrent sequencing (16S rRNA), UV-spectrometry, ICP-MS, FIA and gas chromatography. Using correlation association tests, significant physicochemical changes (P<0.05) were correlated with temporal variations in microbial community composition in six of the target hotsprings. Of these six hotsprings, temperature and pH were the most influential variables associated with community changes and commonly covaried with the Aquificae, Deinococcus-Thermus and Proteobacteria at four sites. Downstream effects of rainfall using rainfall and geothermal bore water datasets could be linked with physicochemical and microbial community changes during the winter months at two of these sites. This study contributes to our understanding of geothermal microbial dynamics in stable and variable geothermal environme nts, and highlights that geothermal hotsprings are not isolated from their surrounding environment.

text: Temporal dynamics of microbial communities in geothermal hotsprings of the Taupo Volcanic Zone Few studies of microbial biogeography address temporal variability in physicochemical conditions and communities in geothermal environments. Here we examine the temporal variability of 43 chemical analytes, temperature and pH in association with microbial community composition of 69 water samples collected bimonthly from 12 hotsprings of the Taupo Volcanic Zone between December 2015 and October 2016. Communities and physicochemical parameters were characterized using a combination of next generation Ion Torrent sequencing (16S rRNA), UV-spectrometry, ICP-MS, FIA and gas chromatography. Using correlation association tests, significant physicochemical changes (P<0.05) were correlated with temporal variations in microbial community composition in six of the target hotsprings. Of these six hotsprings, temperature and pH were the most influential variables associated with community changes and commonly covaried with the Aquificae, Deinococcus-Thermus and Proteobacteria at four sites. Downstream effects of rainfall using rainfall and geothermal bore water datasets could be linked with physicochemical and microbial community changes during the winter months at two of these sites. This study contributes to our understanding of geothermal microbial dynamics in stable and variable geothermal environme nts, and highlights that geothermal hotsprings are not isolated from their surrounding environment.

year: 2017

title: Māori social identities in New Zealand and Hawai'i

authors: Nikora, Linda Waimarie

subjects: Maori

abstract: This research is comprised of two narrative interview studies of Māori in two different settings, New Zealand (n=20) and Hawai'i (n=30).  The data was gathered over the 1994-1996 period.  The two settings have some commonalities and differences.  In both settings Māori are required to make decisions about the continuity of their ethnic Māori identities and hereditary cultural identities of iwi, hapu and whanau, and the part that they wish these identities to play in their daily lives.  The focus of this research was about how Māori create meaning in their lives and maintain their social identities across and within those contexts they move through. 

The findings of this research suggest that Māori in New Zealand continue to value and gain meaning and satisfaction from their cultural collectivities and the social identities derived from them.  However, the results tend to suggest that there are changes in the ways that individuals conceptualise these identities and concomitantly, how they see of themselves.
For New Zealand participants, conceptions of hapu and iwi appear to be converging with an increasing focus on the physicality of marae, its environment and symbolism, and the social events and relationships negotiated in that space.  New Zealand participants saw some hapu and iwi maintenance activities as more legitimate than others.  More value was placed on returning to hapu and iwi homelands however irregular these returns were.  In contrast, conceptions of hapu and iwi held by participants in Hawai'i seemed less intense.  There were few opportunities to engage with other hapu or iwi members.  Being Māori had greater meaning and was understood, probed and valued by others in the culturally plural context of Hawai'i.  For New Zealand participants, being Māori was enacted in the context of being a discriminated, negatively constructed minority.  All were aware of the defining effect that the presence of a dominant majority could have and countered these effects by engaging in social justice and in-group solidarity activities.

The changing identity conceptions held by members of Māori social groups will have implications for a sense of community and social cohesion, for tribal asset management, service delivery and crown settlement processes.  If Māori are redefining and renegotiating their social identities to achieve greater meaning and satisfaction then these changes are important to respond to and recognise.

text: Māori social identities in New Zealand and Hawai'i This research is comprised of two narrative interview studies of Māori in two different settings, New Zealand (n=20) and Hawai'i (n=30).  The data was gathered over the 1994-1996 period.  The two settings have some commonalities and differences.  In both settings Māori are required to make decisions about the continuity of their ethnic Māori identities and hereditary cultural identities of iwi, hapu and whanau, and the part that they wish these identities to play in their daily lives.  The focus of this research was about how Māori create meaning in their lives and maintain their social identities across and within those contexts they move through. 

The findings of this research suggest that Māori in New Zealand continue to value and gain meaning and satisfaction from their cultural collectivities and the social identities derived from them.  However, the results tend to suggest that there are changes in the ways that individuals conceptualise these identities and concomitantly, how they see of themselves.
For New Zealand participants, conceptions of hapu and iwi appear to be converging with an increasing focus on the physicality of marae, its environment and symbolism, and the social events and relationships negotiated in that space.  New Zealand participants saw some hapu and iwi maintenance activities as more legitimate than others.  More value was placed on returning to hapu and iwi homelands however irregular these returns were.  In contrast, conceptions of hapu and iwi held by participants in Hawai'i seemed less intense.  There were few opportunities to engage with other hapu or iwi members.  Being Māori had greater meaning and was understood, probed and valued by others in the culturally plural context of Hawai'i.  For New Zealand participants, being Māori was enacted in the context of being a discriminated, negatively constructed minority.  All were aware of the defining effect that the presence of a dominant majority could have and countered these effects by engaging in social justice and in-group solidarity activities.

The changing identity conceptions held by members of Māori social groups will have implications for a sense of community and social cohesion, for tribal asset management, service delivery and crown settlement processes.  If Māori are redefining and renegotiating their social identities to achieve greater meaning and satisfaction then these changes are important to respond to and recognise.

year: 2007