491 research outputs found

    Assessing the disclosure protection provided by misclassification for survey microdata

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    Government statistical agencies often apply statistical disclosure limitation techniques to survey microdata to protect confidentiality. There is a need for ways to assess the protection provided. This paper develops some simple methods for disclosure limitation techniques which perturb the values of categorical identifying variables. The methods are applied in numerical experiments based upon census data from the United Kingdom which are subject to two perturbation techniques: data swapping and the post randomisation method. Some simplifying approximations to the measure of risk are found to work well in capturing the impacts of these techniques. These approximations provide simple extensions of existing risk assessment methods based upon Poisson log-linear models. A numerical experiment is also undertaken to assess the impact of multivariate misclassification with an increasing number of identifying variables. The methods developed in this paper may also be used to obtain more realistic assessments of risk which take account of the kinds of measurement and other non-sampling errors commonly arising in surveys

    Geographically intelligent disclosure control for flexible aggregation of census data

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    This paper describes a geographically intelligent approach to disclosure control for protecting flexibly aggregated census data. Increased analytical power has stimulated user demand for more detailed information for smaller geographical areas and customized boundaries. Consequently it is vital that improved methods of statistical disclosure control are developed to protect against the increased disclosure risk. Traditionally methods of statistical disclosure control have been aspatial in nature. Here we present a geographically intelligent approach that takes into account the spatial distribution of risk. We describe empirical work illustrating how the flexibility of this new method, called local density swapping, is an improved alternative to random record swapping in terms of risk-utility

    Estimation of the Distribution of Hourly Pay from Household Survey Data: The Use of Missing Data Methods to Handle Measurement Error

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    Measurement errors in survey data on hourly pay may lead to serious upward bias in low pay estimates. We consider how to correct for this bias when auxiliary accurately measured data are available for a subsample. An application to the UK Labour Force Survey is described. The use of fractional imputation, nearest neighbour imputation, predictive mean matching and propensity score weighting are considered. Properties of point estimators are compared both theoretically and by simulation. A fractional predictive mean matching imputation approach is advocated. It performs similarly to propensity score weighting, but displays slight advantages of robustness and efficiency.

    Euler systems for GSp(4)

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    We construct an Euler system for Galois representations associated to cohomological cuspidal automorphic representations of the group GSp(4), using the pushforwards of Eisenstein classes for GL(2) x GL(2).Comment: 41 pages. Revised version -- main theorem now applies in all cohomological weight

    Non-response biases in surveys of schoolchildren: the case of the English Programme for International Student Assessment (PISA) samples

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    We analyse response patterns to an important survey of schoolchildren, exploiting rich auxiliary information on respondents' and non-respondents' cognitive ability that is correlated both with response and the learning achievement that the survey aims to measure. The survey is the Programme for International Student Assessment (PISA), which sets response thresholds in an attempt to control the quality of data. We analyse the case of England for 2000, when response rates were deemed sufficiently high by the organizers of the survey to publish the results, and 2003, when response rates were a little lower and deemed of sufficient concern for the results not to be published. We construct weights that account for the pattern of non-response by using two methods: propensity scores and the generalized regression estimator. There is clear evidence of biases, but there is no indication that the slightly higher response rates in 2000 were associated with higher quality data. This underlines the danger of using response rate thresholds as a guide to quality of data

    Exercise as a Treatment for Conduit Artery Dysfunction in a Comorbid State of Metabolic Syndrome and Depressive-like Symptoms

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    Metabolic Syndrome (Mets) is a clustering of cardiovascular risk factors that results in a three-fold increase in cardiovascular disease. MetS is known to be associated with adverse arterial remodeling, endothelial dysfunction, decreased nitric oxide (NO) bioavailability, increased inflammation, and conduit artery dysfunction. Depression/chronic stress is emerging as a potent contributor to MetS, with MetS also aiding in the progression of depression, and thus increased vascular dysfunction. These bi-directional comorbidities are continually increasing in prevalence, justifying a need for research on their interplay and potential treatments. Aerobic exercise is a widely accepted therapy for the risk factors associated with MetS, mental stress, and vascular dysfunction. However, no study has evaluated the ability of aerobic exercise to combat the vascular dysfunction caused by MetS and depressive-like symptoms. Our objective is to evaluate the effects of MetS, chronic unpredictable stress, and exercise on the conduit arteries. The central hypothesis is aerobic exercise will attenuate the harmful arterial remodeling, endothelial dysfunction, and decreased NO bioavailability caused by MetS and chronic stress

    Flash Flood!: A SeriousGeoGames activity combining science festivals, video games, and virtual reality with research data for communicating flood risk and geomorphology

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    The risk of flooding around the world is large and increasing, yet in many areas there is still a difficulty in engaging the public with their own flood risk. Geomorphology is a science that is linked to flooding and can exacerbate risks, but awareness of the science with the public is low and declining within academia. To increase awareness, it is important to engage the public directly with the science and those who are working to reduce flood risks - this starts by inspiring people to seek out further information through positive experiences of the science and researchers. Here, a new design model is presented to engage the public with specific research projects by using useful components offered by the popular mediums of games, virtual reality (VR), and science festivals to allow the public to get "hands on"with research data and models: SeriousGeoGames. A SeriousGeoGames activity, Flash Flood!, was developed around real geomorphology survey data to help engage the public with a flood-risk-related research project by placing them in a river valley as it undergoes a geomorphically active flooding from an intense rainfall event. Flash Flood! was exhibited at two science-focussed events, and formal evaluation was captured using a short questionnaire, finding that the majority of audience had a positive interaction (95.1%) and wanted to know more about flooding (68.0%) and geomorphology (60.1%). It is hoped these interactions will increase the likelihood that future engagements with relevant agencies will be more fruitful, especially when it matters most

    Non-response biases in surveys of school children: the case of the English PISA samples

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    We analyse response patterns to an important survey of school children, exploiting rich auxiliary information on respondents’ and non-respondents’ cognitive ability that is correlated both with response and the learning achievement that the survey aims to measure. The survey is the Programme for International Student Assessment (PISA), which sets response thresholds in an attempt to control data quality. We analyse the case of England for 2000 when response rates were deemed high enough by the PISA organisers to publish the results, and 2003, when response rates were a little lower and deemed of sufficient concern for the results not to be published. We construct weights that account for the pattern of non-response using two methods, propensity scores and the GREG estimator. There is clear evidence of biases, but there is no indication that the slightly higher response rates in 2000 were associated with higher quality data. This underlines the danger of using response rate thresholds as a guide to data quality.Non-response, bias, school survey, data linkage, PISA

    Comments on the Rao and Fuller (2017) paper

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    This note by Chris Skinner presents a discussion of the paper “Sample survey theory and methods: Past, present, and future directions” where J.N.K. Rao and Wayne A. Fuller share their views regarding the developments in sample survey theory and methods covering the past 100 year

    Apple Pomace as a Novel Aid for Western Diet-Induced Nonalcoholic Fatty Liver Disease in Young Female Sprague Dawley Rats

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    Apple pomace is a “waste” byproduct of apple processing that causes environmental pollution and is costly to dispose of. Yet, apple pomace is rich in dietary fibers and antioxidants. Analysis of apple pomace’s nutritional profile indicates suitability as a potential dietary treatment for non-alcoholic fatty liver disease (NAFLD) and the more severe non-alcoholic steatohepatitis (NASH). NAFLD is the most prevalent liver disease in the world with prevalence and severity expected to increase in both adults and children. Currently, there is no approved drug treatment for NAFLD and therefore, dietary intervention is the primary treatment. The study objectives were to determine the effect of apple pomace consumption on diet-induced NAFLD, NASH and renal and bone health using a rodent model. Growing (aged 22-29 d) female Sprague-Dawley rats (n=8/group) were fed ad libitum diets consisting of AIN-93G, AIN-93G with 10% apple pomace substitution (AIN/AP), Western diet (45% fat, 34% sucrose), or Western diet with 10% apple pomace substitution (Western/AP) for 8 weeks. Results showed Western diet consumption increased (pp reaction (RT-qPCR) showed rats consuming Western diet upregulated hepatic expression of diacylglycerol O-acyltransferase 2 (DGAT2), which was attenuated by apple pomace. Rats consuming Western diets also had upregulated nuclear factor kappa-light chain enhancer of activated B cells (NFκB) and interleukin-6 (IL-6). Further, gonadal adipose tissue expression of NFκB, IL-6, and tumor necrosis factor alpha (TNFα) was significantly upregulated compared to all groups contributing to progression of NAFLD to NASH. The results suggest increased gonadal adipose also increased transport of inflammatory cytokines, resulting in NASH progression. Apple pomace attenuated Western diet-induced NAFLD due to the high fiber content in apple pomace increasing (
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