SCREENING DISABILITY INSURANCE APPLICATIONS

This paper investigates the effects of stricter screening of disability insurance applications. A large‐scale experiment was set up wherein two of the 26 Dutch regions caseworkers of the disability insurance administration were instructed to screen applications more stringently. The empirical results show that stricter screening reduces long‐term sickness absenteeism and disability insurance applications. We find evidence for direct effects of stricter screening on work resumption during the period of sickness absence and for self‐screening by potential disability insurance applicants. Furthermore, stricter screening improves targeting efficiency without inducing negative spillover effects on the inflow into unemployment insurance.     

Inventory Control when the Lead‐time Changes

A single‐echelon inventory system with continuous review and Poisson demand is considered. There are standard linear holding and backorder costs but no ordering or set‐up costs. We study a change in the lead‐time, which is rather typical in connection with application of a Just‐In‐Time philosophy. Our main focus is a lead‐time decrease but we also consider a lead‐time increase. Due to the lead‐time change, the optimal steady state solution will also, in general, change. We consider the transient problem of minimizing the costs when bringing the system from its original steady state to the new steady state.     

Adult Foreign Adoptees: Reactive Attachment Disorder May Grow into Psychic Homelessness

The heterogeneity of the group of adopted children does not allow to draw general conclusions about the nature and quantity of behavioral problems with adopted children. This nature and quantity depend on the chosen comparison group. Older foreign adoptees at placement often show complex physical and psychological problems. Many suffer from some kind of behavioral disturbances. Empirical data show that reactive attachment disorder (RAD) can often be diagnosed. The continuation of this disorder in adulthood will result in feelings of psychic homelessness. Examples are described to make clear what kind of behavioral problem it concerns. Research to select appropriate treatments for RAD and psychic homelessness is still lacking.     

Calculating China’s Historical Economic Aggregate: A GDP-centered Overview*

Since the 1990s, thanks to the concerted efforts of domestic and international scholars, the research on China’s historical GDP that began in the 1930s has received widespread attention, and is becoming a widely discussed issue at the forefront of research on world economic history. At the same time, several scholars at home and abroad have also voiced a call for more theoretical and empirical reflection within this line of research. Diversification of methods, systematic reconstruction of historical data, and international comparisons represent three emerging trends in future research on this subject. By encouraging and leading these trends, Chinese scholars can assume a greater role in international research on economic history.     

Determinants of species richness within and across taxonomic groups in urban green spaces

Urban green spaces provide habitat for numerous plant and animal species. However, currently we have little knowledge on which determinants drive the species richness within and across taxonomic groups. In this paper we investigate the determinants of total, native, and endangered species richness for vascular plants, birds, and mammals within and across taxonomic groups. We examined a stratified random sample of 32 urban green spaces in Hannover, Germany. Species inventories for plants and birds were generated on the basis of line transect surveys. Mammals were surveyed by means of point counts using camera traps. Using a principal component analysis and multiple regression models, we tested 10 explanatory variables for species-area effects, distance effects, and the effects of habitat structure of green spaces on species richness. When analyzing single explanatory variables, we determined that the species richness of all groups was significantly positively correlated to patch area, number of habitat types, and a short distance to the nearest green space. Testing combined effects of variables showed that patch area in combination with habitat heterogeneity was most important for plants (total, native, and endangered), birds (total and native), and overall species richness. This emphasizes the importance of the species-area effect and the effects of habitat structure on species richness in urban green spaces. We conclude that, in the context of urban planning, it is important to conserve large green spaces that include a high diversity of habitats to maintain high species richness.     

Do We Need Computer Skills to Use a Computer? Evidence from Britain

Abstract. Using cross‐section data from the 1997 Skills Survey of the Employed British Workforce, we examine the labour‐market returns to self‐assessed computer skills in Britain. Many researchers, using information on computer technology use, have concluded that wage differentials between computer users and non‐users might, among others, be due to differences in the embodiment of computer skills. Using unique information on the importance, level of sophistication, and effectiveness of computer technology use, we show that computer skills do not yield significant labour‐market returns for most types of use. Examining the returns to computer skills at different levels of sophistication of use yields estimates suggesting returns to computer skills at the highest level of sophistication of use only.     

Asymptotic Inference for Jump Diffusions with State‐Dependent Intensity

We establish the local asymptotic normality property for a class of ergodic parametric jump‐diffusion processes with state‐dependent intensity and known volatility function sampled at high frequency. We prove that the inference problem about the drift and jump parameters is adaptive with respect to parameters in the volatility function that can be consistently estimated.     

Dutch Adolescents’ Motives,Perceptions, and Reflections Toward Sex-Related Internet Use: Results of a Web-Based Focus-Group Study

The Internet offers adolescents unique opportunities to actively shape their own sexual media environment. The aim of this study was to gain in-depth insight into Dutch adolescents’ motives, perceptions, and reflections toward Internet use for (a) finding information or advice related to romance and sexuality; (b) searching for and viewing pornographic or erotic material; and (c) romantic and sexual communication (i.e., cybersex/sexting). Data were collected through 12 Web-based focus groups (36 adolescents aged 16 to 19 years, 72.2% girls) and analyzed through three stages of open, axial, and selective coding. The themes that emerged from the focus-group discussions suggest that sex-related Internet use is a complex and ambivalent experience for adolescents. Sex-related Internet use seems an increasingly normalized and common phenomenon. Participants perceived the Internet as a useful source of sexual information, stimulation, inspiration, and communication. Yet they discussed a range of negative consequences and risks related to sex-related online behaviors, particularly concerning pornography’s potential to create unrealistic expectations about sex and sexual attractiveness. Participants generally believed they had the necessary skills to navigate through the online sexual landscape in a responsible way, although they believed other young people could be influenced inadvertently and adversely by sex-related online content.     

Growing old and staying young: population policy in an ageing closed economy

This paper analyses the relation between public pensions, fertility and child care in a closed-economy overlapping generations model with endogenous fertility. It is shown that raising a child involves two social externalities and that it is optimal to introduce child allowances if the government redistributes income from the young to the old. The optimal child allowance rises when longevity increases. If the costs of raising children depend positively on the wage, a third externality arises and the returns to savings should be taxed.