Towards a European migration policy

The stagnating West European population combined with the prosperous economic development of the European Community (EC) generate strong economic incentives for immigration. The drastic political changes in Eastern Europe have caused additional migration pressures. There are a variety of problems with the economic and political integration of migrants, however. The paper argues that immigration can compensate for demographic losses due to the decline and ageing of the European labor force. Economic theory further predicts welfare gains from free factor movements, which should be reaped as long as social costs and adjustment costs are not prohibitive. An active European migration policy is recommended to achieve this aim.This article is a completely revised version of CEPR Discussion Paper No. 641, presented by the second author at the CEPR Workshop The economies of migration on 23 November 1991 in London, UK, and at a hearing of the European Parliament on 25 May 1992 in Bruxelles, Belgium.     

Estimation of energy expenditure using accelerometers and activity-based energy models��validation of a new device

Over the last few years, the estimation of energy expenditure with accelerometers has become more and more accurate due to improvements in sensor technology. Significant enhancement could be reached by model-based estimation regarding different activity types. The kmsMove-sensor (movisens GmbH, Karlsruhe, Germany) is a device that is used to compute human energy expenditure using motion-dependent calculation models. It is outfitted with an accelerometer to measure body acceleration during certain movements and activities. To validate its accuracy, the sensor was compared to indirect calorimetry as criterion measure. For this experiment, nine subjects (all males, age 46.4 ± 10.9 years, 28–64 years) were equipped with the kmsMove-sensor as well as a portable indirect calorimeter and their energy consumption was measured over a time period of 100 min. Additionally, the energy consumption of seven out of the above-mentioned nine subjects was measured over an average of 7 h. The measurements took place in a rehabilitation clinic, where the subjects completed their regular daily rehabilitation activities. An analysis of the data revealed ICCs between the kmsMove-sensor and indirect calorimetry for the time period of 100 min of 0.82 (0.38–0.96; p = 0.003) and for an averaged measuring time of 7 h of 0.81 (0.22–0.97; p = 0.01). Furthermore, a Bland–Altman analysis for the time period of 100 min led to a difference of the means of 4.3 kcal (limits of agreement: −94.3 and 102.9 kcal) and for the time period of an average of 7 h to −14.0 kcal (limits of agreement: −320.0 and 292.0 kcal). These findings indicate that the kmsMove-sensor is an appropriate measuring device with relatively good accuracy to assess human energy expenditure in rehabilitation patients. However, this study has some limiting aspects (small sample size, artificial setting) which could influence validity.     

Expertentum und eskalierendes Commitment

The present study examines the role of expertise for the escalation of commitment. Subjects were 56 apprentices of the financial services sector and 46 subjects working as first-aid persons. Subjects were confronted with scenarios stemming from both areas of work and they had to decide about the allocation of further financial resources after a failing investment. Commitment was measured through the amount of additional investments. The independent variable ?expertise“ was manipulated by the combination of sample and job-context: Those, who had to decide about further investments in the condition with the scenario stemming from their own area of work, were considered to be experts whereas those who were confronted with the scenario of the unfamiliar work-setting were rated as novices. Results show that escalating commitment was significantly higher for novices than for experts.     

生命周期不同阶段的幽默理解与加工机制

以往学者们大多将幽默作为一种语言现象进行研究,几乎没人关注幽默的神经心理加工过程。现代脑成像技术给学者们提供了一种更为客观的方式,有助于揭开幽默大脑加工的神秘面纱。尽管幽默的认知神经心理机制的研究已经能够帮助人们建立起对人类幽默理解的系统认识,但目前还有很多可扩展的方向：首先,目前的绝大多数研究都以成年人为研究对象,研究的外部效度存在问题,仅有个别研究着眼于儿童和老年人的幽默理解认知机制,应该开展针对其他年龄段的研究,从人类生命周期的角度整合不同年龄段的幽默理解神经心理加工机制发展变化的特点。其次,应着重结合汉语的特点和我国社会发展的特点进行研究,形成中国特色的汉语幽默认知加工理论。     

Loss prediction based on run-off triangles

Loss reserving is an important subject of actuarial mathematics. It aims at the prediction of future losses caused by claims which have incurred in the past but have not yet been closed. The problem of predicting such losses is particularly important in liability insurance. More generally, it is most relevant with respect to the new regulatory requirements for insurance companies operating in the European Union, which are known as Solvency II.     

Demographic change, endogenous labor supply and the political feasibility of pension reform

Options for reforming unfunded public pension schemes that are now being discussed all share the feature that the burden induced by demographic change would be shifted towards presently living and away from unborn generations. Existing models of the political economy of pension reform can not explain why such reform options are being discussed at all. We present an alternative model in which the possibility of evasion of workers from payment of social security taxes is taken into account by modelling a labor supply function. It turns out that the burden of demographic change may fall completely or at least predominantly on the pensioners. Thus this type of model can much better explain recent trends in legislature on unfunded public pension systems in industrial democracies. Received: 7 January 1999/Accepted: 20 December 1999     

Maximum-likelihood and marginal-sum estimation in some particular collective models

In the present paper we consider collective models in risk theory and their thinning and decomposition. We give three applications to reinsurance, multiplicative tariffs, and loss reserving. For each of these applications we show how maximum-likelihood and marginal-sum estimation can be used to estimate the parameters.