Real‐Time Delay Estimation Based on Delay History in Many‐Server Service Systems with Time‐Varying Arrivals

Motivated by interest in making delay announcements in service systems, we study real‐time delay estimators in many‐server service systems, both with and without customer abandonment. Our main contribution here is to consider the realistic feature of time‐varying arrival rates. We focus especially on delay estimators exploiting recent customer delay history. We show that time‐varying arrival rates can introduce significant estimation bias in delay‐history‐based delay estimators when the system experiences alternating periods of overload and underload. We then introduce refined delay‐history estimators that effectively cope with time‐varying arrival rates together with non‐exponential service‐time and abandonment‐time distributions, which are often observed in practice. We use computer simulation to verify that our proposed estimators outperform several natural alternatives.     

The potential power of social policy programmes: income redistribution,economic resources and health

Lundberg O, Fritzell J, Åberg Yngwe M, Kölegård ML. The potential power of social policy programmes: income redistribution, economic resources and health Int J Soc Welfare 2010: ??: ??–??© 2010 The Author(s), Journal compilation © 2010 Blackwell Publishing Ltd and International Journal of Social Welfare. This Supplement includes a number of articles dealing with the role of social policy schemes for public health across the life course. As a key social determinant of health, poverty and its consequences have historically been at the forefront of the public health discussion. But also in rich countries today, economic resources are likely to be important for health and survival, both on an individual and an aggregate level. This introductory article serves as a background for the more specific analyses that follow. The focus is on why income and income inequality could have an effect on individual and population health. We discuss relationships between the individual and population levels and between income and health, and some of the possible mechanisms involved. We also present arguments for why welfare state institutions may matter.     

Trends of Income Inequality Among the Elderly in Korea

This study investigates the overall trend of inequality among the elderly in Korea and to examine what the most influential factor is for these changes. Although inequality among the elderly is far greater than it is for any other group, little attention has been given to how inequality changes over time. Used are data from the Urban Household Survey with five‐year intervals from 1986 to 2006. The results show that inequality within a cohort increases over time and that earnings and benefits from occupational retirement plans are the most influential factors on overall inequality changes. In addition, the impact of public transfers has gradually increased during the past twenty years. The results imply that our society needs to enact a social policy for lessening earnings inequality in the labor market and to increase public transfers for the elderly.     

Statistical Inference and Applications of Mixture of Varying Coefficient Models

In this paper, we consider a new mixture of varying coefficient models, in which each mixture component follows a varying coefficient model and the mixing proportions and dispersion parameters are also allowed to be unknown smooth functions. We systematically study the identifiability, estimation and inference for the new mixture model. The proposed new mixture model is rather general, encompassing many mixture models as its special cases such as mixtures of linear regression models, mixtures of generalized linear models, mixtures of partially linear models and mixtures of generalized additive models, some of which are new mixture models by themselves and have not been investigated before. The new mixture of varying coefficient model is shown to be identifiable under mild conditions. We develop a local likelihood procedure and a modified expectation–maximization algorithm for the estimation of the unknown non‐parametric functions. Asymptotic normality is established for the proposed estimator. A generalized likelihood ratio test is further developed for testing whether some of the unknown functions are constants. We derive the asymptotic distribution of the proposed generalized likelihood ratio test statistics and prove that the Wilks phenomenon holds. The proposed methodology is illustrated by Monte Carlo simulations and an analysis of a CO₂‐GDP data set.     

Pseudo Panel Data Models With Cohort Interactive Effects

When genuine panel data samples are not available, repeated cross-sectional surveys can be used to form so-called pseudo panels. In this article, we investigate the properties of linear pseudo panel data estimators with fixed number of cohorts and time observations. We extend standard linear pseudo panel data setup to models with factor residuals by adapting the quasi-differencing approach developed for genuine panels. In a Monte Carlo study, we find that the proposed procedure has good finite sample properties in situations with endogeneity, cohort interactive effects, and near nonidentification. Finally, as an illustration the proposed method is applied to data from Ecuador to study labor supply elasticity. Supplementary materials for this article are available online.     

基于用户规模的双边平台适应性动态定价策略研究

鉴于交叉网络效应导致用户加入双边平台的效用随用户规模动态变化,提出根据用户规模进行适应性动态定价的策略思想,并运用数值计算方法对该定价策略的效果进行深入研究。首先,引入平台动态竞争建模方法,构建了包含用户规模的双边平台适应性动态定价模型;接着,根据数值计算结果对动态定价与静态定价的效果进行比较;最后,考察了平台竞争主要参数的变化对动态定价策略效果的影响。研究表明：（1）动态定价显著优于静态定价,模型主要参数的取值变动不会改变动态定价具有相对优势这个定性结论;（2）提升服务质量或改变基准用户数不会明显增加动态定价的相对优势,但强交叉网络效应或前瞻性用户都会增强动态定价的相对优势。研究结果有助于平台企业管理者更好地制定平台定价策略。     

Extrapolative simulation of neighborhood networks based on population spatial distribution: Do they predict crime?

Objectives

Previous criminological scholarship has posited that network ties among neighborhood residents may impact crime rates, but has done little to consider the specific ways in which network structure may enhance or inhibit criminal activity. A lack of data on social ties has arguably led to this state of affairs. We propose to avoid this limitation by demonstrating a novel approach of extrapolatively simulating network ties and constructing structural network measures to assess their effect on neighborhood crime rates.

Methods

We first spatially locate the households of a city into their constituent blocks. Then, we employ spatial interaction functions based on prior empirical work and simulate a network of social ties among these residents. From this simulated network, we compute network statistics that more appropriately capture the notions of cohesion and information diffusion that underlie theories of networks and crime.

Results

We show that these network statistics are robust predictors of the levels of crime in five separate cities (above standard controls) at the very micro geographic level of blocks and block groups.

Conclusions

We conclude by considering extensions of the approach that account for homophily in the formation of network ties.     

Exponential random graph models of preschool affiliative networks

Exponential random graph models were used to assess the relevance of reciprocity, popularity, transitivity controlling for effects based upon ego and alter sex, and sex homophily, on the formation of affiliative ties in 19 Portuguese preschool peer groups. The number of times two children were recorded as nearest neighbors in focal samples was used as an indicator of the relationship's strength. Independent parameter estimates of the different models (one for each group) were summarized, separately for the three age groups (“3-year-olds”, “4-year-olds” and “5-year-olds”) using a multi-level approach to meta-analysis. Results showed that affiliative ties between children were sex segregated, highly reciprocal, more likely to be directed to a restricted number of children and with a tendency to create transitive triads. The structural processes underlying the formation of affiliative ties were quite stable between classrooms.     

Perceptions About Residence Hall Wingmates and Alcohol-Related Secondhand Effects Among College Freshmen

Objective: The authors examined the secondhand effects among college freshmen of others' alcohol use and related student characteristics, and perceptions about residence hallmates.

Participants: The authors surveyed 509 incoming freshmen residing in predominantly freshman residence halls.

Methods: The authors administered a Web-based survey 2 months into the 2006 fall academic semester.

Results: Most (80%) students experienced at least 1 secondhand effect. Participants' perceptions of wingmates' acceptance and expectation of alcohol use and participants' perceived inability to protect themselves against alcohol problems were related to experiencing secondhand effects, as were being a female and a drinker.

Conclusions: Incoming college freshmen frequently experienced secondhand effects of alcohol use. Involving residence halls in norms-based interventions aimed at reducing secondhand effects warrants evaluation. Further research is also needed to examine skill building among college students to avoid and intervene into others' drinking and to examine resident advisor roles as both engenderers of trust and cooperation as well as enforcers of alcohol rules.     

Daughter's Perceptions of Being Mothered by an Incest Survivor: A Phenomenological Study

ABSTRACT

This article presents the results of a qualitative analysis of the experience of being the daughter of an incest survivor using a phenomenological approach to the narratives of six women. The majority of the daughters identified a number of effects of their mother's abuse that they perceived as harmful as a child and that lasted into adulthood. Most perceived their mothers as failing to grow up. The daughters responded with a lack of affection toward their mothers, complications in differentiation and integration of a negative self-view. Even in adulthood, the daughters reported a number of characteristics that are normally associated with being a victim of sexual abuse, despite the fact that only two of the six had been so abused. The mother's ultimate disclosure of her incest history helped the daughter to offset these difficulties. The clinical implications of these findings are outlined.