title: Conditional density estimation with class probability estimators

authors: Frank, Eibe

subjects: computer science

abstract: Many regression schemes deliver a point estimate only, but often it is useful or even essential to quantify the uncertainty inherent in a prediction. If a conditional density estimate is available, then prediction intervals can be derived from it. In this paper we compare three techniques for computing conditional density estimates using a class probability estimator, where this estimator is applied to the discretized target variable and used to derive instance weights for an underlying univariate density estimator; this yields a conditional density estimate. The three density estimators we compare are: a histogram estimator that has been used previously in this context, a normal density estimator, and a kernel estimator. In our experiments, the latter two deliver better performance, both in terms of cross-validated log-likelihood and in terms of quality of the resulting prediction intervals. The empirical coverage of the intervals is close to the desired confidence level in most cases. We also include results for point estimation, as well as a comparison to Gaussian process regression and nonparametric quantile estimation.

text: Conditional density estimation with class probability estimators Many regression schemes deliver a point estimate only, but often it is useful or even essential to quantify the uncertainty inherent in a prediction. If a conditional density estimate is available, then prediction intervals can be derived from it. In this paper we compare three techniques for computing conditional density estimates using a class probability estimator, where this estimator is applied to the discretized target variable and used to derive instance weights for an underlying univariate density estimator; this yields a conditional density estimate. The three density estimators we compare are: a histogram estimator that has been used previously in this context, a normal density estimator, and a kernel estimator. In our experiments, the latter two deliver better performance, both in terms of cross-validated log-likelihood and in terms of quality of the resulting prediction intervals. The empirical coverage of the intervals is close to the desired confidence level in most cases. We also include results for point estimation, as well as a comparison to Gaussian process regression and nonparametric quantile estimation.

year: 2009

title: Natural and Experimental Admixture of Invasive Blowflies in New Zealand and Australia

authors: Croft, Lillian

abstract: Across the globe, native species are being outcompeted and often reach extinction due to introduced species becoming invasive. Previously confined to their native areas due to geographical, ecological, or environmental barriers that have prevented them from expanding, human impacts have resulted in a significant increase in the number of introduced species. Such species become invasive when they begin to expand their range demographically and typically cause negative impacts in the new environment. There is no current model that allows us to predict and prevent future biological invasions, though next generation sequencing, population genomics analysis, and experimental laboratory manipulations are helping to fill critical gaps in our understanding of the invasion process. 
My first analysis (Chapter 2) explored the ability of population genetics analyses of single nucleotide polymorphism (SNP) data to identify hybridisation levels and the rate of admixture occurring in wild populations of Calliphora hilli and Calliphora stygia – two invasive blowflies found in New Zealand and originally from Australia. I analysed samples from various locations and found patterns of population genetic connectivity and structure that supported Australia as the source of the New Zealand invasion for both species. This research provided highly valuable new insights into the population structure of these two species, with hybridisation and gene flow playing a key role in their respective biological invasions. 
My second analysis (Chapter 3) first explored the population structure of the highly invasive blowfly species, Callipohra vicina, using SNP data to analyse population genomic patterns, such as genetic diversity and admixture. Following this, low genetic diversity colonies were generated from isofemale lines to simulate an invasive population that had undergone a genetic bottleneck. These low diversity lines were compared to relatively high diversity lines for a number of traits, including fecundity, body size, developmental rate, and lifespan to determine the effects of genetic diversity on population fitness. We found genetic differentiation between North and South Island New Zealand populations in the wild, while high diversity lines outcompeted low diversity lines for all measured traits in the laboratory. These results demonstrated the importance of genetic bottlenecks on invasion scenarios and suggested interesting new ideas for follow-up research.
Predicting and preventing future invasions is a significant current gap in invasion biology. Population genomic and ecological assays can together help to fill this gap to help us identify the mechanisms underlying invasive success.

text: Natural and Experimental Admixture of Invasive Blowflies in New Zealand and Australia Across the globe, native species are being outcompeted and often reach extinction due to introduced species becoming invasive. Previously confined to their native areas due to geographical, ecological, or environmental barriers that have prevented them from expanding, human impacts have resulted in a significant increase in the number of introduced species. Such species become invasive when they begin to expand their range demographically and typically cause negative impacts in the new environment. There is no current model that allows us to predict and prevent future biological invasions, though next generation sequencing, population genomics analysis, and experimental laboratory manipulations are helping to fill critical gaps in our understanding of the invasion process. 
My first analysis (Chapter 2) explored the ability of population genetics analyses of single nucleotide polymorphism (SNP) data to identify hybridisation levels and the rate of admixture occurring in wild populations of Calliphora hilli and Calliphora stygia – two invasive blowflies found in New Zealand and originally from Australia. I analysed samples from various locations and found patterns of population genetic connectivity and structure that supported Australia as the source of the New Zealand invasion for both species. This research provided highly valuable new insights into the population structure of these two species, with hybridisation and gene flow playing a key role in their respective biological invasions. 
My second analysis (Chapter 3) first explored the population structure of the highly invasive blowfly species, Callipohra vicina, using SNP data to analyse population genomic patterns, such as genetic diversity and admixture. Following this, low genetic diversity colonies were generated from isofemale lines to simulate an invasive population that had undergone a genetic bottleneck. These low diversity lines were compared to relatively high diversity lines for a number of traits, including fecundity, body size, developmental rate, and lifespan to determine the effects of genetic diversity on population fitness. We found genetic differentiation between North and South Island New Zealand populations in the wild, while high diversity lines outcompeted low diversity lines for all measured traits in the laboratory. These results demonstrated the importance of genetic bottlenecks on invasion scenarios and suggested interesting new ideas for follow-up research.
Predicting and preventing future invasions is a significant current gap in invasion biology. Population genomic and ecological assays can together help to fill this gap to help us identify the mechanisms underlying invasive success.

year: 2024

title: Art, the aesthetics, and ethics of tattooing at Flax Roots Tattoo Studio

authors: Shaver, Mandy (Amanda)

subjects: aesthetic

abstract: Flax Roots Tattoo Studio, a tattoo business in Hamilton, Waikato, New Zealand, offers clients different styles of tattooing to choose from, i.e. Moko, Traditional European, Portrait, and Traditional American. Tattoo artists and their clients differ in ethnicity, nationality, religion, sex, occupation, age, hobbies, and so on.  Anthropological research and philosophical insight provided the framework texts for my case study.  My fieldwork consisted of semi-structured interviews and photographs of artists and clients.  By participating in tattooing, these individuals influence the art and the aesthetic tastes of their local culture.  Additionally, tattoo artists follow an ethical code that dictates how to run their business, preserve their art, and protect their clients.  By choosing Flax Roots Tattoo Studio as my fieldwork site, I was able to answer the questions: 1. How do tattoo artists and their clients engage with and shape tattoo art and its aesthetic at Flax Roots Tattoo Studio? ; and 2. How do these tattoo artists’ ethics influence their relationships with their clients and art?

text: Art, the aesthetics, and ethics of tattooing at Flax Roots Tattoo Studio Flax Roots Tattoo Studio, a tattoo business in Hamilton, Waikato, New Zealand, offers clients different styles of tattooing to choose from, i.e. Moko, Traditional European, Portrait, and Traditional American. Tattoo artists and their clients differ in ethnicity, nationality, religion, sex, occupation, age, hobbies, and so on.  Anthropological research and philosophical insight provided the framework texts for my case study.  My fieldwork consisted of semi-structured interviews and photographs of artists and clients.  By participating in tattooing, these individuals influence the art and the aesthetic tastes of their local culture.  Additionally, tattoo artists follow an ethical code that dictates how to run their business, preserve their art, and protect their clients.  By choosing Flax Roots Tattoo Studio as my fieldwork site, I was able to answer the questions: 1. How do tattoo artists and their clients engage with and shape tattoo art and its aesthetic at Flax Roots Tattoo Studio? ; and 2. How do these tattoo artists’ ethics influence their relationships with their clients and art?

year: 2018