Self-generated fertility waves in a non-linear continuous overlapping generations model

In this paper, Samuelson's simplified version of the Easterlin theory (Samuelson 1976) is extended to a continuous-time model with three age groups. This approach enables one to apply the qualitative theory of non-linear differential equations to show the existence of Easterlin-type cycles. In contrast to the discrete time model we obtain information about the period length of the cycle.This research was supported by the Austrian Science Foundation under grant P6601.     

Capital accumulation,endogenous population growth,and Easterlin cycles

In this paper we attempt to explain the occurrence of population cycles in industrialised economies where the birth rate depends on the difference between the actual and the expected consumption rate. This model of an endogenously growing population brings together Easterlin's idea of an adapting aspiration level with the neoclassical optimal growth paradigm. It is shown that in this highly aggregated demo-economic system (i.e., without inclusion of the age structure of a population) swings both in the economic and demographic variables may exist. The reason behind this strange optimal behaviour is identified to be an intertemporal substitution effect between current and future levels of consumption.We wish to thank A. Novak for helpful assistance and an anonymous referee for useful comments. Financial support by the Austrian Science Foundation under contract No. P6601 is acknowledged.     

The effect of fast and slow decisions on risk taking

We experimentally compare fast and slow decisions in a series of experiments on financial risk taking in three countries involving over 1700 subjects. To manipulate fast and slow decisions, subjects were randomly allocated to responding within 7 seconds (time pressure) or waiting for at least 7 or 20 seconds (time delay) before responding. To control for different effects of time pressure and time delay on measurement noise, we estimate separate parameters for noise and risk preferences within a random utility framework. We find that time pressure increases risk aversion for gains and risk taking for losses compared to time delay, implying that time pressure increases the reflection effect of Prospect Theory. The results for gains are weaker and less robust than the results for losses. We find no significant difference between time pressure and time delay for loss aversion (tested in only one of the experiments). Time delay also leads to less measurement noise than time pressure and unconstrained decisions, and appears to be an effective way of decreasing noise in experiments.     

重振布隆方丹中央商务区：前景、阻碍与错失的机会

一个多世纪以来,人们对城市变迁展开了系统性的研究,其中一个焦点是城市的中央商务区（CBDs）。过去几十年里有大量关于中央商务区衰落问题的文献,焦点集中在这种衰退为什么会发生,以及可以出台哪些刺激性政策措施来重振这些地区。本文主要讨论大城市中较为发达的地区,从地理上说就是南非北部的前工业重镇。就这些问题南非的学者也有为数不多但值得我们重视的文献,他们以年鉴形式记录了中央商务区的衰落及后续的重振措施。与国际上的经验类似,研究的焦点集中在南非的主要大城市地区,而二线城市则不在研究者们关注的范围之内。本文概述二线城市布隆方丹的中央商务区重振所面临的前景和阻碍的目的是,尽管在开普敦和约翰内斯堡等城市开展一般性的重振项目对抑制中央商务区的进一步衰退有显著成效,但对布隆方丹这样的二线城市来说,可能还需要一些其他措施。     

Made sense and remembered sense: Sensemaking through abduction

The purpose of this article is threefold: to present a general framework for investigating processes of reasoning and problem solving in market-related situations that are not transparent, to present some central processes involved in sensemaking, and to present a set of key elements of abductive reasoning. The paper focuses on the processes involved in making sense, on the on-line generation of explanations, and on logics more suitable for on-line and commonsense reasoning than classical logic. Although some of the roots of experts' reasoning must be aleatory (probabilistic), the focus of the paper is epistemic (causal) reasoning in ill-structured domains. The professional decision maker is seen as equipped with a diverse mental toolbox. The on-line making of new sense is a process that we are only beginning to understand. Likewise, the process involved in strategy shift and the changing of mind are not well understood. Nonmonotonic, abductive reasoning is presented as a framework within which we can start to understand, and possibly re-evaluate on-line and creative economic decision making.     

Book Reviews

Book Review

Book Reviews     

Type a behaviour and back pain

Type A behaviour and back pain     

Zur Erlernung optimalen Verhaltens in Entscheidungssituationen

Statistical Papers -     

MAXIMUM PRINCIPLE FOR AGE AND DURATION STRUCTURED SYSTEMS: A TOOL FOR OPTIMAL PREVENTION AND TREATMENT OF HIV

Age and duration since infection are considered in a model of optimal control of the spread of Human Immunodeficiency Virus (HIV) in countries with high prevalence. Prevention and medical treatment are selected so as to maximize an economic objective function.The model extends the classical McKendrick equation. Necessary optimality conditions in the form of Pontryagin's global maximum principle and numerical solution based on them are presented. “Critical” initial prevalence is established numerically for which there are two optimal medical treatments: one intense and another less demanding. It is shown that treatment alone can be counterproductive: increase in treatment must be accompanied by increase in prevention.