Confidence Corridors for Multivariate Generalized Quantile Regression

We focus on the construction of confidence corridors for multivariate nonparametric generalized quantile regression functions. This construction is based on asymptotic results for the maximal deviation between a suitable nonparametric estimator and the true function of interest, which follow after a series of approximation steps including a Bahadur representation, a new strong approximation theorem, and exponential tail inequalities for Gaussian random fields. As a byproduct we also obtain multivariate confidence corridors for the regression function in the classical mean regression. To deal with the problem of slowly decreasing error in coverage probability of the asymptotic confidence corridors, which results in meager coverage for small sample sizes, a simple bootstrap procedure is designed based on the leading term of the Bahadur representation. The finite-sample properties of both procedures are investigated by means of a simulation study and it is demonstrated that the bootstrap procedure considerably outperforms the asymptotic bands in terms of coverage accuracy. Finally, the bootstrap confidence corridors are used to study the efficacy of the National Supported Work Demonstration, which is a randomized employment enhancement program launched in the 1970s. This article has supplementary materials online.     

The potential of a couples approach to employment assistance: results of a nonexperimental evaluation

We present findings from a nonexperimental evaluation of an employment program in which both partners in young, low-income, primarily African-American couples simultaneously participated. Mothers participating in the couples program had larger immediate gains in employment and earnings and decreases in TANF receipt following their exit from the program relative to mothers who received employment assistance as individuals. Fathers showed similar although weaker results. These immediate benefits appeared to be driven by higher rates of program completion among couples’ participants. Couples in which both partners completed the program experienced the largest quarterly earnings gains, and couples with greater earnings’ gains were more likely to still be together one year after the program ended. Mothers’ earnings gains eroded in the two years following program completion and many reported new pregnancies and problems with child care. We suggest directions for future programs and encourage future studies to consider the range of mechanisms associated with a couples focus, including potential motivational benefits and unintended consequences.

Modellgestützte Flexibilitätsanalyse von Strategien zur Ersatzteilversorgung in der Nachserienphase

An important task in after sales service is the provision of spare parts for durables. Due to its nature and dependence on earlier sales, the demand for spare parts is inherently dynamic and uncertain requiring for high procurement flexibility. During the product life cycle, inventory management of spare parts is performed efficiently under use of flexibility provided by existing production facilities. This situation completely changes once the OEM ceases production of the parent product. A prime option of procuring spare parts for the End-of-production period is to place a final order for parts when regular production ends. Besides low unit production costs, this option does not contain any flexibility, yielding a high risk of obsolescence of stored parts, and at the same time a high risk of not being able to satisfy all demand during the service period. In order to increase flexibility further options like extra production at higher unit cost or remanufacturing of components taken from used products could be used. After introducing the problem and a basic quantitative model, we evaluate flexibility properties of strategies using different combinations of the above options. In doing so we distinguish between quantity, time, and stock related flexibility. In a comprehensive numerical study it is investigated to which extent flexibility properties of the different strategies can contribute to their economic profitability.     

Squirrels in suburbia: influence of urbanisation on the occurrence and distribution of a common exotic mammal

Urbanisation is widely considered to promote the establishment of non-native species, but there is limited empirical evidence of the ecological factors driving their responses. The grey squirrel Sciurus carolinensis (Gmelin 1788) is native to North America, but is widespread in the UK and is starting to spread across Europe. It is regarded as one of the world’s worst invasive animals due to its adverse impacts on native biodiversity. We use the non-native grey squirrel population in Sheffield (UK) as a case study to assess which factors limit its distribution and abundance in urban environments. In 2010 the city-wide population of adult squirrels peaked at an estimated 6539 in autumn (0.46 squirrels/ha), with maximum local densities of 8.29/ha. These densities appear to be slightly lower than those recorded in urban environments in the species’ native range. Grey squirrels occurred more frequently at urban sites with larger amounts of green-space in the surrounding region. Local habitat characteristics were, however, more powerful predictors of urban grey squirrel occurrence and abundance than regional availability of green space. Canopy cover, seed bearing trees and supplementary feeders, provided for garden birds, positively influenced grey squirrels. The potential for grey squirrels to connect city dwellers with nature thus appears to be highest in urban locations that have considerable capacity to support native biodiversity. The beneficial impacts of supplementary feeding on grey squirrel populations is notable given concerns that squirrels can adversely influence bird populations. These habitat associations also imply that grey squirrels typically respond negatively to urbanisation, which challenges arguments that urbanisation favours exotic species.     

Nativity and Self‐Assessed Health among Pre‐Retirement Age Hispanics and Non‐Hispanic Whites1

Economic, social and familial resources are known to influence subjective health assessments. We examine the salience of nativity in determining how these resources influence self‐assessed health using a large, nationwide sample of Hispanic and non‐Hispanic white adults. The results indicate that while education, accumulated assets and marital status benefit the physical and emotional health of the native and foreign‐born, family resources and income are significant only for the native‐born. English language proficiency is a significant protective factor for both groups and is especially protective for immigrants. These surprising findings call into question previous studies stressing the positive role of the family in maintaining immigrant health.     

Making ends meet,in the household and on the planet

Policy‐making in relation to sustainable development is usually at the national (or, in relation to climate change, the global) level, yet the consumption it seeks to modify takes place at the household level. If households all ‘made ends meet’ in the same way then the much‐relied‐upon notion of per capita consumption would be valid and we could use ‘top‐down’ modelling to guide policy. Cultural Theory, however, predicts that there are five socially viable ways of making ends meet, and that all of them will be found (in varying proportions) within any nation. This prediction has been tested on a sample of 220 British households and shown to be well supported. Top‐down modelling, it is argued, has to give way to constructive interplay between the reflexive policy‐maker and a plurally responsive citizenry.     

The Courtship Dance: Patterns of Nonverbal Synchronization in Opposite-Sex Encounters

This study examines the existence of behavioral correlates of synchronization on different levels of analysis and methods. We were unable to demonstrate a relation between synchronization defined in terms of movement echo or position mirroring and subjective experience of pleasure and interest in opposite-sex encounters. Significant results were found for a phenomenon we describe as hierarchically patterned synchronization. These patterns were identified with the help of a newly developed search algorithm. If a female is interested in a male, highly complex patterns of behavior with a constant time structure emerge. The patterns are pair-specific and independent from behavioral content. This rhythmic structure of interactions is discussed in functional terms of human courtship.     

应用EMME／2宏语言执行道路定价模型

香港的交通拥挤非常严重，而且好像并不能通过增加道路容量来解决，考虑到大多数拥挤地区空间的限制和增加道路容量所导致的潜在需求，交通规划人员和经济专家们为解决交通拥挤问题，已经把他们的注意力从交通供方面转移交通需求上。道路定价方法可构成交通需求管理战略的一部分，为交通拥挤问题提供了一个有效、公平、灵活的解决方案。香港特共政府已指定了一个咨询机构，来调查电子道路定价系统的需求，以及执行后的社会反应，为了