1,520 research outputs found

    Clustering South African households based on their asset status using latent variable models

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    The Agincourt Health and Demographic Surveillance System has since 2001 conducted a biannual household asset survey in order to quantify household socio-economic status (SES) in a rural population living in northeast South Africa. The survey contains binary, ordinal and nominal items. In the absence of income or expenditure data, the SES landscape in the study population is explored and described by clustering the households into homogeneous groups based on their asset status. A model-based approach to clustering the Agincourt households, based on latent variable models, is proposed. In the case of modeling binary or ordinal items, item response theory models are employed. For nominal survey items, a factor analysis model, similar in nature to a multinomial probit model, is used. Both model types have an underlying latent variable structure - this similarity is exploited and the models are combined to produce a hybrid model capable of handling mixed data types. Further, a mixture of the hybrid models is considered to provide clustering capabilities within the context of mixed binary, ordinal and nominal response data. The proposed model is termed a mixture of factor analyzers for mixed data (MFA-MD). The MFA-MD model is applied to the survey data to cluster the Agincourt households into homogeneous groups. The model is estimated within the Bayesian paradigm, using a Markov chain Monte Carlo algorithm. Intuitive groupings result, providing insight to the different socio-economic strata within the Agincourt region.Comment: Published in at http://dx.doi.org/10.1214/14-AOAS726 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

    An update on oral cavity cancer:epidemiological trends, prevention strategies and novel approaches in diagnosis and prognosis

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    In the UK, the incidence of oral cavity cancer continues to rise, with an increase of around 60% over the past 10 years. Many patients still present with advanced disease, often resulting in locoregional recurrence and poor outcomes, which has not changed significantly for over four decades. Changes in aetiology may also be emerging, given the decline of smoking in developed countries. Therefore, new methods to better target prevention, improve screening and detect recurrence are needed. High-throughput ‘omics’ technologies appear promising for future individual-level diagnosis and prognosis. However, given this is a relatively rare cancer with significant intra-tumour heterogeneity and variation in patient response, reliable biomarkers have been difficult to elucidate. From a public health perspective, implementing these novel technologies into current services would require substantial practical, financial and ethical considerations. This may be difficult to justify and implement at present, therefore focus remains on early detection using new patient-led follow-up strategies. This paper reviews the latest evidence on epidemiological trends in oral cavity cancer to help identify at risk groups, population-based approaches for prevention, in addition to potential cutting-edge approaches in the diagnosis and prognosis of this disease. Keywords: Epidemiology, Oral Cancer, Survival, Risk Factors, Squamous Cell Carcinoma, Mouth Neoplasm

    A Benefit-Cost Analysis of the Tulsa Universal Pre-K Program

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    In this paper, benefits and costs are estimated for a universal pre-K program, provided by Tulsa Public Schools. Benefits are derived from estimated effects of Tulsa pre-K on retention by grade 9. Retention effects are projected to dollar benefits from future earnings increases and crime reductions. Based on these estimates, Tulsa pre-K has benefits exceeding costs by about 2-to-1. This benefit cost ratio is far less than the benefit-cost ratios (ranging from 8-to-1 to 16-to-1) for more targeted and intensive pre-K programs from the 1970s and 80s, such as Perry Preschool and the Chicago Child-Parent Center (CPC) program. Comparing benefit-cost results from different studies suggests that our more modest estimates are due to two factors: 1) smaller percentage effects of pre-K on future earnings and crime in Tulsa than in Perry and CPC, and 2) smaller baseline crime rates in Tulsa than in the Perry and CPC comparison groups

    A Benefit-Cost Analysis of the Tulsa Universal Pre-K Program

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    In this paper, benefits and costs are estimated for a universal pre-K program, provided by Tulsa Public Schools. Benefits are derived from estimated effects of Tulsa pre-K on retention by grade 9. Retention effects are projected to dollar benefits from future earnings increases and crime reductions. Based on these estimates, Tulsa pre-K has benefits exceeding costs by about 2-to-1. This benefit cost ratio is far less than the benefit-cost ratios (ranging from 8-to-1 to 16-to-1) for more targeted and intensive pre-K programs from the 1970s and 80s, such as Perry Preschool and the Chicago Child-Parent Center (CPC) program. Comparing benefit-cost results from different studies suggests that our more modest estimates are due to two factors: 1) smaller percentage effects of pre-K on future earnings and crime in Tulsa than in Perry and CPC, and 2) smaller baseline crime rates in Tulsa than in the Perry and CPC comparison groups

    Effects of the Pre-K Program of Kalamazoo County Ready 4s on Kindergarten Entry Test Scores: Estimates Based on Data from the Fall of 2011 and the Fall of 2012

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    This paper uses a regression discontinuity model to examine the effects on kindergarten entrance assessments of the Kalamazoo County Ready 4s (KC Ready 4s) program, a half-day pre-K program for four-year-olds in Kalamazoo County, Michigan. The results are based on test scores and other characteristics of up to 220 children participating in KC Ready 4s, with data coming from both 2011–2012 and 2012–2013 participants in the program. The estimates find consistently statistically significant effects of this pre-K program on improving entering kindergartners’ math test scores. Some estimates also suggest marginally statistically significant effects of KC Ready 4s on vocabulary test scores. No statistically significant effects are found on letter-word identification test scores, due in part to the small available sample size, but some of the point estimates are large. The program does not appear to have large or statistically significant effects in improving children’s behavioral assessments. The overall average effects of KC Ready 4s on the three academic test scores are large, at an effect size of at least 0.52. This is toward the high end of effects found in previous studies of short-term effects of pre-K programs. These estimates also are consistent with program benefits exceeding program costs

    The Uses of Chiral Anomaly for Determination of the Number of Colors

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    The NcN_c-dependence of the vertices PPPγPPP\gamma, where PP is a pseudoscalar meson and NcN_c is the number of colors, is analyzed with regard for the NcN_c-dependence of the quark charges. It is shown that the best processes for the determination of NcN_c are the reactions Kγ→KπK\gamma \to K\pi and πpmγ→π±η\pi^pm\gamma\to\pi^\pm\eta as well as the decay \eta\ra\pi^+\pi^-\gamma. The measurement of the cross section \sigma(\pi^-\gamma\ra\pi^-\eta) at the VES facility at the IHEP agrees with the value Nc=3N_c=3.Comment: 7 pages, 1 figure; accepted to Phys. Atom. Nucl., references adde
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