The performance of techniques for estimating the number of eligible signatories to a large petition on the basis of a sample of signatures : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Statistics at Massey University, Palmerston North, New Zealand

The New Zealand Citizens' Initiated Referenda Act, 1993, states that if a petition signed by at least 10 percent of eligible electors is presented to the House of Representatives, then parliament is required to hold an indicative referendum on the petition. Normal practice at present is to check a sample of the signatures and from that estimate the number of eligible electors who have signed a petition, making allowance for signatories who are not eligible and multiple signatures from eligible electors. We review a number of techniques used for similar problems such as estimating the size of a population through capture-recapture studies, or estimating the number of duplicate entries in a mailing list. One suitable estimator was developed by Goodman (1949). A number of variants on it are reported by Smith-Cayama & Thomas (1999). An estimator proposed by Esty (1985) was found to give unreasonable estimates, and so a modification was developed. In order to test the performance of the modified estimator, simulations, drawing repeated samples from artificial petitions with known distributions of multiple signatures, were performed. The simulation results allowed us to investigate bias in the estimators and the accuracy of the variance estimates proposed by Hass & Stokes (1998). The effect of sampling fraction on bias, variability and estimated variance of the estimators was also investigated. The simulation program was modified to include ineligible signatures. Results of these simulations showed that estimating the number of ineligible signatures added to the variability of the overall estimate of number of eligible signatories. Although Smith-Cayama & Thomas (1999) mention that the estimated number of multiple eligible signatures and the estimated number of ineligible signatures are correlated, the simulations suggest the correlation is small and makes little difference to the final estimate of variability

Software Development Methods and Tools: a New Zealand study

This study is a more detailed follow-up to a preliminary investigation of the practices of software engineers in New Zealand. The focus of this study is on the methods and tools used by software developers in their current organisation. The project involved detailed questionnaires being piloted and sent out to several hundred software developers. A central part of the research involved the identification of factors affecting the use and take-up of existing software development tools in the workplace. The full spectrum of tools from fully integrated I-CASE tools to individual software applications, such as drawing tools was investigated. This paper describes the project and presents the findings

Gut microbiota responses to dietary fibre sources in rats fed starch-based or quasi-human background diets

The effects of whole foods and food components on gut microbiota are often investigated in animal models not fed a human-type background diet. In this study, rats were fed basal starch (BS) or quasi human (QH) background diets either unsubstituted (controls) or substituted with inulin, dried kiwifruit or pectin for 28 days. Gut microbiota composition and hydrated faecal bulking potential of the diets were evaluated. In the caecum and colon, relative abundance of bacteria at the phylum, family or genus levels differed considerably between the background diets (BS and QH). Rats fed QH diets had higher Actinobacteria than those rats fed BS diets. Gut microbiota responses to inulin, kiwifruit and pectin depended on the background diet. QH diet led to twice the mass of hydrated faecal bulk than BS diet. Overall, simple laboratory animal diets are unlikely to provide valid predictions of effects of prebiotics added to human diets

Kiwifruit Non-Sugar Components Reduce Glycaemic Response to Co-Ingested Cereal in Humans

Kiwifruit (KF) effects on the human glycaemic response to co-ingested wheat cereal were determined. Participants (n = 20) consumed four meals in random order, all being made to 40 g of the same available carbohydrate, by adding kiwifruit sugars (KF sug; glucose, fructose, sucrose 2:2:1) to meals not containing KF. The meals were flaked wheat biscuit (WB)+KFsug, WB+KF, WB+guar gum+KFsug, WB+guar gum+KF, that was ingested after fasting overnight. Blood glucose was monitored 3 h and hunger measured at 180 min post-meal using a visual analogue scale. KF and guar reduced postprandial blood glucose response amplitude, and prevented subsequent hypoglycaemia that occurred with WB+KFsug. The area between the blood glucose response curve and baseline from 0 to 180 min was not significantly different between meals, 0–120 min areas were significantly reduced by KF and/or guar. Area from 120 to 180 min was positive for KF, guar, and KF+guar, while the area for the WB meal was negative. Hunger at 180 min was significantly reduced by KF and/or guar when compared with WB. We conclude that KF components other than available carbohydrate may improve the glycaemic response profile to co-ingested cereal food

Detection of non-pathogenic and pathogenic populations of Vibrio parahaemolyticus in various samples by the conventional, quantitative and droplet digital PCRs

Abstract In this study, three generations of polymerase chain reaction (PCR) assays: (i) conventional PCR, (ii) qPCR and (iii) droplet digital PCR (ddPCR), were systematically tested for their abilities to detect non-pathogenic and pathogenic populations of Vibrio parahaemolyticus. The limit of detection (LOD) for the ddPCR was 1.1 pg/µL of purified DNA, followed by the qPCR (5.6 pg/µL) and the conventional PCR (8.8 pg/µL). Regarding the LOD for V. parahaemolyticus cells, the ddPCR assay was able to detect 29 cells, followed by the conventional PCR assay (58 cells) and the qPCR assay (115 cells). Regarding the sensitivities to detect this pathogen from PCR inhibition prone samples (naturally contaminated mussels), the ddPCR assay significantly outperformed the conventional PCR and qPCR. The ddPCR assay was able to consistently detect non-pathogenic and pathogenic populations of V. parahaemolyticus from naturally contaminated mussels, indicating its tolerance to various PCR inhibitors. This study also revealed the significant difference between conventional PCR and qPCR. The conventional PCR assay showed significantly greater sensitivity than that of the qPCR assay in detecting V. parahaemolyticus in crude samples, whereas the qPCR assay showed better sensitivity in detecting the presence of V. parahaemolyticus in purified DNA samples

Avaliação da intenção de compra de couve minimamente processada Consumer intention to purchase for minimally processed cabbage

Vários fatores influenciam a percepção do produto pelo consumidor e, conseqüentemente, sua intenção de compra. Dentre tais fatores pode estar a expectativa criada pelas características da embalagem e do rótulo, pois representam o primeiro contato entre o indivíduo e o produto. O objetivo desse trabalho foi avaliar o efeito das características da embalagem na intenção de compra de couve minimamente processada, considerando as diferenças individuais dos consumidores para processar as informações. Cinco características da embalagem de couve minimamente processada (informação, tipo de produção, cor, preço e visibilidade do produto) foram manipuladas e 12 embalagens criadas seguindo delineamento fatorial incompleto. A intenção de compra para o produto foi avaliada por 144 consumidores baseada apenas na observação das referidas embalagens. Os dados foram analisados utilizando Conjoint e Cluster Analyses. Os resultados apontaram para um segmento único de consumidores, composto por indivíduos com percepção do produto bastante similar quanto à intenção de compra. Dentre as características da embalagem, a informação foi a que obteve maior importância relativa (77%), enfatizando seu papel na intenção de compra para esse grupo de consumidores. Em seguida, o tipo de produção, cor e preço também contribuíram significativamente (p<0,0001) na intenção de compra de couve minimamente processada, havendo maior intenção de compra para a embalagem com a característica "sem produtos químicos" e preço baixo.<br>Several factors affect the consumer product perception and, consequently, his/her intention to purchase. Among such factors is the expectation which can be created by the food label/packaging, which represents the first contact between the person and the product. This study aimed at investigating the effect of the manipulated package characteristics on the consumer intention to purchase for minimally processed cabbage, taking into account the consumer individual differences. Five minimally processed cabbage package characteristics (information, production type, colour, price and product visibility) were manipulated yielding 12 packages, according to a fractional factorial design. The intention to purchase for cabbage was evaluated by 144 consumers based only on the package observation. The data were analysed using Conjoint and Cluster Analyses. Only one segment of consumers was identified, where participants had very similar intention to purchase. Information had highest relative importance (77%) revealing its role for participants. The production type, colour and price also had a significant effect (p<0.0001) on the consumer intention to purchase for minimally processed cabbage. A higher intention to purchase was observed for the "with no chemical products" and "low price" package

Vineyard-wide control of grapevine leafroll-associated virus 3 requires an integrated response

Grapevine leafroll-associated virus 3 (GLRaV-3) negatively alters grape yield and wine quality but adopting practical control actions could avert an epidemic. In 13 New Zealand commercial vineyards that were planted with one of five red berry cultivars (n = 29,943 vines), we assessed if roguing (removing) GLRaV-3-infected vines could reduce and maintain incidence at <1%. In 2009, baseline GLRaV-3 incidence ranged from 4 to 24%. Annually until 2015, we visually diagnosed and rogued vines with foliar symptoms of GLRaV-3, and monitored vine populations of the virus vector, the mealybug Pseudococcus calceolariae. In 2009, 2544 symptomatic vines (12%) were rogued but with incidence declining year-on-year, just 408 vines (1.4%) were rogued in 2015. Mapping virus spread annually showed within-row vines immediately either side of an infected vine (‘first’ vines) were most at risk of vector mediated transmission, but a temporal decline in these infections was observed. In 2010, 26%of ‘first’ vines had foliar symptoms, reducing to 6% by 2015. Overall, GLRaV-3 management outcomes were variable. In six vineyards, symptomatic vine incidence reduced to <1% within 3 years of roguing commencing. By contrast, roguing did not contain virus spread in another two vineyards, where cumulative vine losses of 37 and 46% to 2011 and 2013, respectively, was deemed economically unsustainable by the owners who removed all remaining vines. In the remaining five vineyards, annual incidence was consistently ˃1%. In demonstrating the importance of low vector pressure to successful virus control, we emphasise the need to adopt a multi-tactic response targeting virus and vector populations annually.This work formed part of the New Zealand Grape and Wine Research programme, jointly funded by New Zealand Winegrowers Inc. (NZW) and The New Zealand Institute for Plant & Food Research (PFR) Strategic Science Investment Fund.https://link.springer.com/journal/421612019-10-01am2019Forestry and Agricultural Biotechnology Institute (FABI)Microbiology and Plant Patholog