4,708 research outputs found
On the occurrence times of componentwise maxima and bias in likelihood inference for multivariate max-stable distributions
Full likelihood-based inference for high-dimensional multivariate extreme
value distributions, or max-stable processes, is feasible when incorporating
occurrence times of the maxima; without this information, -dimensional
likelihood inference is usually precluded due to the large number of terms in
the likelihood. However, some studies have noted bias when performing
high-dimensional inference that incorporates such event information,
particularly when dependence is weak. We elucidate this phenomenon, showing
that for unbiased inference in moderate dimensions, dimension should be of
a magnitude smaller than the square root of the number of vectors over which
one takes the componentwise maximum. A bias reduction technique is suggested
and illustrated on the extreme value logistic model.Comment: 7 page
An Analysis of Major Farm Characteristics and Farmers' Use of Cooperatives
This paper examines relationships between major farm characteristics and U.S. farmersâ use of cooperatives in 1986. An ordinal measure of co-op use is developed to classify farmers according to their respective use of cooperatives for marketing farm products or purchasing farm inputs. Logit regression analysis is then used to examine major farm characteristics relative to farmersâ co-op use. Statistically significant relationships were found between co-op use and various farm type, size, and location groupings. No statistically significant relationship was found between co-op use and farm operator age.Agribusiness,
Accounting for choice of measurement scale in extreme value modeling
We investigate the effect that the choice of measurement scale has upon
inference and extrapolation in extreme value analysis. Separate analyses of
variables from a single process on scales which are linked by a nonlinear
transformation may lead to discrepant conclusions concerning the tail behavior
of the process. We propose the use of a Box--Cox power transformation
incorporated as part of the inference procedure to account parametrically for
the uncertainty surrounding the scale of extrapolation. This has the additional
feature of increasing the rate of convergence of the distribution tails to an
extreme value form in certain cases and thus reducing bias in the model
estimation. Inference without reparameterization is practicably infeasible, so
we explore a reparameterization which exploits the asymptotic theory of
normalizing constants required for nondegenerate limit distributions. Inference
is carried out in a Bayesian setting, an advantage of this being the
availability of posterior predictive return levels. The methodology is
illustrated on both simulated data and significant wave height data from the
North Sea.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS333 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Labour market performance of immigrants in the UK labour market
From executive summary:
This document is a report commissioned by the Home Office to analyse the performance of immigrants in the UK labour market. It attempts to draw a comprehensive picture of
the labour market performance of immigrants, and the process of adaptation relative to the UK-born white population. Four indicators of economic performance are investigated: (i) employment, (ii) labour force participation, (iii) self-employment, and (iv) wages. The
analysis distinguishes between males and females, and between groups of different origin. The effects of specific variables on these outcomes are investigated in detail. The report also considers labour market outcomes of ethnic minority individuals who are born in the UK, and compares their outcomes with those of UK-born white individuals, and of ethnic minority individuals who are foreign-born
Superplastic forming of ceramic insulation
Superplasticity has been demonstrated in many fine-grained structural ceramics and ceramic composites, including yttria-stabilized tetragonal zirconia polycrystal (YTZP), alumina, and Al2O3-reinforced zirconia (Al2O3/YTZ) duplex composites and SiC-reinforced Si3N4. These superplastic ceramics obviously offer the potential benefit of forming net shape or near net shape parts. This could be particularly useful for forming complicated shapes that are difficult to achieve using conventional forming techniques, or require elaborate, subsequent machining. In the present study, we successfully demonstrated the following: (1) superplastic 3Y-TXP and 20 percent Al2O3/YTZ composite have for the first time been successfully deformed into hemispherical caps via a biaxial gas-pressure forming technique; (2) no experimental difficulty was encountered in applying the required gas pressures and temperatures to achieve the results, thus, it is certain that higher rates of deformation than those presented in this study will be possible by using the current test apparatus at higher temperatures and pressures; and (3) an analytical model incorporating material parameters, such as variations during forming in the strain rate sensitivity exponent and grain growth-induced strain hardening, is needed to model accurately and therefore precisely control the biaxial gas-pressure forming of superplastic ceramics. Based on the results of this study, we propose to fabricate zirconia insulation tubes by superplastic extrusion of zirconia polycrystal. This would not only reduce the cost, but also improve the reliability of the tube products
Probabilistic latent semantic analysis as a potential method for integrating spatial data concepts
In this paper we explore the use of Probabilistic Latent Semantic Analysis (PLSA) as a method for quantifying semantic differences between land cover classes. The results are promising, revealing âhiddenâ or not easily discernible data concepts. PLSA provides a âbottom upâ approach to interoperability problems for users in the face of âtop downâ solutions provided by formal ontologies. We note the potential for a meta-problem of how to interpret the concepts and the need for further research to reconcile the top-down and bottom-up approaches
Improving Nursing Program Climate, Knowledge, and Attitudes toward LGBTQ+ Health and Healthcare
Purpose
To implement an educational intervention and examine the effects of the intervention on nursing student and faculty perceptions of nursing program climate, knowledge, and attitudes regarding LGBTQ+ health and healthcare
Experimental Realization of a One-way Quantum Computer Algorithm Solving Simon's Problem
We report an experimental demonstration of a one-way implementation of a
quantum algorithm solving Simon's Problem - a black box period-finding problem
which has an exponential gap between the classical and quantum runtime. Using
an all-optical setup and modifying the bases of single-qubit measurements on a
five-qubit cluster state, key representative functions of the logical two-qubit
version's black box can be queried and solved. To the best of our knowledge,
this work represents the first experimental realization of the quantum
algorithm solving Simon's Problem. The experimental results are in excellent
agreement with the theoretical model, demonstrating the successful performance
of the algorithm. With a view to scaling up to larger numbers of qubits, we
analyze the resource requirements for an n-qubit version. This work helps
highlight how one-way quantum computing provides a practical route to
experimentally investigating the quantum-classical gap in the query complexity
model.Comment: 9 pages, 5 figure
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