Component selection and smoothing in multivariate nonparametric regression

We propose a new method for model selection and model fitting in multivariate nonparametric regression models, in the framework of smoothing spline ANOVA. The ``COSSO'' is a method of regularization with the penalty functional being the sum of component norms, instead of the squared norm employed in the traditional smoothing spline method. The COSSO provides a unified framework for several recent proposals for model selection in linear models and smoothing spline ANOVA models. Theoretical properties, such as the existence and the rate of convergence of the COSSO estimator, are studied. In the special case of a tensor product design with periodic functions, a detailed analysis reveals that the COSSO does model selection by applying a novel soft thresholding type operation to the function components. We give an equivalent formulation of the COSSO estimator which leads naturally to an iterative algorithm. We compare the COSSO with MARS, a popular method that builds functional ANOVA models, in simulations and real examples. The COSSO method can be extended to classification problems and we compare its performance with those of a number of machine learning algorithms on real datasets. The COSSO gives very competitive performance in these studies.Comment: Published at http://dx.doi.org/10.1214/009053606000000722 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Effect of leading-edge geometry on boundary-layer receptivity to freestream sound

The receptivity to freestream sound of the laminar boundary layer over a semi-infinite flat plate with an elliptic leading edge is simulated numerically. The incompressible flow past the flat plate is computed by solving the full Navier-Stokes equations in general curvilinear coordinates. A finite-difference method which is second-order accurate in space and time is used. Spatial and temporal developments of the Tollmien-Schlichting wave in the boundary layer, due to small-amplitude time-harmonic oscillations of the freestream velocity that closely simulate a sound wave travelling parallel to the plate, are observed. The effect of leading-edge curvature is studied by varying the aspect ratio of the ellipse. The boundary layer over the flat plate with a sharper leading edge is found to be less receptive. The relative contribution of the discontinuity in curvature at the ellipse-flat-plate juncture to receptivity is investigated by smoothing the juncture with a polynomial. Continuous curvature leads to less receptivity. A new geometry of the leading edge, a modified super ellipse, which provides continuous curvature at the juncture with the flat plate, is used to study the effect of continuous curvature and inherent pressure gradient on receptivity

Guangzhou Buyers Preference for Premium Hawaiian Grown Product Gift Baskets

Guangzhou buyers' preference for premium Hawaiian grown product gift baskets with conjoint analysis was examined. Relative importance of three gift basket attributes: container type, products origin, and price were examined. Expenditure equivalent index to evaluate how much more each of the gift basket attributes is worth to the buyer was estimated. Main conclusions are: products have to be 'made in Hawaii' to receive the premium price; business buyers are generally less willing to pay a high price; and individual buyers are more willing to pay the higher priced Koa gift basket.Chinese survey data, conjoint analysis, buyer preference, Hawaii gift baskets, Demand and Price Analysis,

An Analysis on the Formation and Cultivation of Environmental Protection Norms in the Context of Green Gamification

Currently, individual green behaviors have attracted great attention from many countries for environmental degradation. It is particularly critical to identify useful strategies to motivate users’ green behaviors. Based on the goal framing theory, this paper considers three target motivations (hedonic goal, gain goal, and normative goal) of users’ behaviors, proposes the formation and cultivation mechanics of green behaviors in the green gamification platform, and builds a model considering the process of users’ engagement. By comparing users’ quality situation (high, general, low), this paper concludes that a lower involvement degree is required by high-quality individuals when forming and cultivating an environmental behavior habit. The result also benefits organizations that apply gamification designs in varieties of ways to engage and steer users like employees or consumers toward targeted goals

Household screening and multidrug-resistant tuberculosis

Of the estimated half a million people who develop multidrug resistant (MDR) tuberculosis each year, less than 7% are diagnosed and only 1 in 5 of these have access to eff ective treatment.1 To control this epidemic, dramatically increased efforts are required to scale up case detection and treatment provision. In The Lancet, Mercedes Becerra and colleagues2 report the yield of additional MDR tuberculosis diagnoses that are found by screening household contacts of index cases in Lima, Peru. This study—the largest of its kind to date—found that more than 2% of 4503 household contacts had active tuberculosis at the time the index case was diagnosed. Incident tuberculosis was also found at a rate of 1624 cases per 100 000 person-years over 4 years follow-up. These results support recommendations for active screening of household contacts of people with MDR tuberculosis,3 and provide valuable lessons for other programmes striving to improve case detection and to reduce community transmission of MDR tuberculosis

Harnessing Technology Schools Survey 2009: data report - part 2, data analysis

This document sets out the details of the sampling processes and the methodology of the 2009 Schools Survey and the choices made in organising the analysis

Use of Oral Anticoagulant for Secondary Prevention of Stroke in Very Elderly Patients With Atrial Fibrillation: An Observational Study

SummaryBackgroundOral anticoagulant (OAC) is proven to be more effective than antiplatelet therapy in the secondary prevention of ischemic stroke in patients with atrial fibrillation (AF). The objective of this study was to determine the effect of age on the prescription of OAC and its actual use by neurologists for secondary prevention among the very elderly patients with AF hospitalized for ischemic stroke.MethodsIn this prospective observational study, data from patients with first-ever ischemic stroke and AF were included. We reviewed the use of antithrombotic agents before stroke onset and at discharge in patients with AF who were aged 80 years or older. We analyzed the trends of oral anticoagulation as secondary prevention in very elderly patients and identify the reasons why anticoagulant was not prescribed at discharge.ResultsA total of 152 patients with AF experienced first-ever ischemic stroke. Of these, 51 patients (33.6%) were ≥80 years of age, and 101 were <80 years of age. Thirteen patients died during the acute stroke and thus were excluded from the analysis. Of 139 ischemic stroke survivors at discharge, 45 were ≥80 years of age and 94 were <80 years of age. For those aged ≥80 years, 62.2% received neither antiplatelet nor anticoagulant agents before stroke onset. Surprisingly, only one patient (2.2%) was treated with OAC. At discharge, only 12 patients (26.7%) aged ≥80 years were treated with OAC compared with those aged <80 years (48/94 [51.1%]).ConclusionThis study suggests that OAC is underused in most of the very elderly patients despite its proven efficacy. A history of stroke did alter the trend of use of antithrombotic agents in this age group