title: Not all estimators are born equal: The empirical properties of some estimators of long memory

authors: Rea, William

subjects: Global dependence

abstract: We present the results of a simulation study into the properties of 12 different estimators of the Hurst parameter, H, or the fractional integration parameter, d, in long memory time series which are available in R packages. We compare and contrast their performance on simulated Fractional Gaussian Noises and fractionally integrated series with lengths between 100 and 10,000 data points and H values between 0.55 and 0.90 or d values between 0.05 and 0.40. We apply all 12 estimators to the Campito Mountain data and estimate the accuracy of their estimates using the Beran goodness-of-fit test for long memory time series.

text: Not all estimators are born equal: The empirical properties of some estimators of long memory We present the results of a simulation study into the properties of 12 different estimators of the Hurst parameter, H, or the fractional integration parameter, d, in long memory time series which are available in R packages. We compare and contrast their performance on simulated Fractional Gaussian Noises and fractionally integrated series with lengths between 100 and 10,000 data points and H values between 0.55 and 0.90 or d values between 0.05 and 0.40. We apply all 12 estimators to the Campito Mountain data and estimate the accuracy of their estimates using the Beran goodness-of-fit test for long memory time series.

year: 2012

title: Fast Algorithms for Nearest Neighbour Search

authors: Kibriya, Ashraf Masood

subjects: Nearest Neighbour

abstract: The nearest neighbour problem is of practical significance in a number of fields. Often we are interested in finding an object near to a given query object. The problem is old, and a large number of solutions have been proposed for it in the literature. However, it remains the case that even the most popular of the techniques proposed for its solution have not been compared against each other. Also, many techniques, including the old and popular ones, can be implemented in a number of ways, and often the different implementations of a technique have not been thoroughly compared either.


  This research presents a detailed investigation of different implementations of two popular nearest neighbour search data structures, KDTrees and Metric Trees, and compares the different implementations of each of the two structures against each other. The best implementations of these structures are then compared against each other and against two other techniques, Annulus Method and Cover Trees. Annulus Method is an old technique that was rediscovered during the research for this thesis. Cover Trees are one of the most novel and promising data structures for nearest neighbour search that have been proposed in the literature.

text: Fast Algorithms for Nearest Neighbour Search The nearest neighbour problem is of practical significance in a number of fields. Often we are interested in finding an object near to a given query object. The problem is old, and a large number of solutions have been proposed for it in the literature. However, it remains the case that even the most popular of the techniques proposed for its solution have not been compared against each other. Also, many techniques, including the old and popular ones, can be implemented in a number of ways, and often the different implementations of a technique have not been thoroughly compared either.


  This research presents a detailed investigation of different implementations of two popular nearest neighbour search data structures, KDTrees and Metric Trees, and compares the different implementations of each of the two structures against each other. The best implementations of these structures are then compared against each other and against two other techniques, Annulus Method and Cover Trees. Annulus Method is an old technique that was rediscovered during the research for this thesis. Cover Trees are one of the most novel and promising data structures for nearest neighbour search that have been proposed in the literature.

year: 2007

title: Neighbours at Puhoi River: A cross-cultural dual biography of Te Hemara Tauhia(1815-1891) and Martin Krippner(1817-1894)

authors: Eddy, Anne

subjects: Cross-cultural

abstract: This thesis seeks to re-construct the biographies of two relatively obscure, yet fascinating and controversial players in the history of Aotearoa New Zealand. Both historical figures were initiators and leaders of neighbouring settlements: the rangatira, Te Hemara Tauhia (1815 – 1891), in his role as chief of the Te Kawerau/Ngāti Rongo hapū of the Ngāti Whātua iwi, re-occupying ancestral lands after living in captivity with Ngāpuhi, and the former Austrian captain, Martin Krippner (1817 – 1894), organiser of an Austrian-Bohemian settlement made possible under the Auckland Provincial Government land grant scheme. Despite their efforts for each community, both men were accused by their own people of misusing their positions for personal gains. Te Hemara Tauhia was blamed for selling off tribal lands to cover personal debts. Martin Krippner was never forgiven for promising his Bohemian compatriots a ‘land of milk and honey’ while leading them to near starvation and struggle within dense New Zealand bush, and subsequently into war in the Waikato where Krippner was commissioned captain in the Waikato Militia.
Focussing on three main objectives, this cross-cultural dual biography provides an original contribution to historical scholarship: Firstly, it looks behind the myths that have been created around Te Hemara Tauhia and Martin Krippner; it thoroughly examines what both men did and how social, economic and political circumstances influenced their motivations and choices at that particular time. Secondly, placing Tauhia’s and Krippner’s biographies side-by-side provides a novel view of a range of historical phenomena from both Tangata Whenua (indigenous peoples) and European settlers (Pākehā) perspectives. Looking at the same events from different angles and perspectives, a cross-cultural, dual biography can act like a prismatic tool, revealing the complexity of a shared history. The third aim of this research encompasses my intention to contribute to and to participate in a dialogue between ethnic groups in Aotearoa New Zealand, especially between Māori and Pākehā, in order to challenge stereotypes and generalisations based on lack of knowledge of historical and cultural contexts.

text: Neighbours at Puhoi River: A cross-cultural dual biography of Te Hemara Tauhia(1815-1891) and Martin Krippner(1817-1894) This thesis seeks to re-construct the biographies of two relatively obscure, yet fascinating and controversial players in the history of Aotearoa New Zealand. Both historical figures were initiators and leaders of neighbouring settlements: the rangatira, Te Hemara Tauhia (1815 – 1891), in his role as chief of the Te Kawerau/Ngāti Rongo hapū of the Ngāti Whātua iwi, re-occupying ancestral lands after living in captivity with Ngāpuhi, and the former Austrian captain, Martin Krippner (1817 – 1894), organiser of an Austrian-Bohemian settlement made possible under the Auckland Provincial Government land grant scheme. Despite their efforts for each community, both men were accused by their own people of misusing their positions for personal gains. Te Hemara Tauhia was blamed for selling off tribal lands to cover personal debts. Martin Krippner was never forgiven for promising his Bohemian compatriots a ‘land of milk and honey’ while leading them to near starvation and struggle within dense New Zealand bush, and subsequently into war in the Waikato where Krippner was commissioned captain in the Waikato Militia.
Focussing on three main objectives, this cross-cultural dual biography provides an original contribution to historical scholarship: Firstly, it looks behind the myths that have been created around Te Hemara Tauhia and Martin Krippner; it thoroughly examines what both men did and how social, economic and political circumstances influenced their motivations and choices at that particular time. Secondly, placing Tauhia’s and Krippner’s biographies side-by-side provides a novel view of a range of historical phenomena from both Tangata Whenua (indigenous peoples) and European settlers (Pākehā) perspectives. Looking at the same events from different angles and perspectives, a cross-cultural, dual biography can act like a prismatic tool, revealing the complexity of a shared history. The third aim of this research encompasses my intention to contribute to and to participate in a dialogue between ethnic groups in Aotearoa New Zealand, especially between Māori and Pākehā, in order to challenge stereotypes and generalisations based on lack of knowledge of historical and cultural contexts.

year: 2017