The average number of events per time unit and its estimation

Let ζ _t be the number of events which will be observed in the time interval [0;t] and define as the average number of events per time unit if this limit exists. In the case of i.i.d. waiting-times between the events,E[ζ _t ] is the renewal function and it follows from well-known results of renewal theory thatA exists and is equal to 1/τ, if τ>0 is the expectation of the waiting-times. This holds true also when τ = ∞.A may be estimate by ζ _t /t or where is the mean of the firstn waiting-timesX ₁,X ₂, ...,X _n . Both estimators converage with probability 1 to 1/τ if theX _i are i.i.d.; but the expectation of may be infinite for alln and also if it is finite, is in general a positively biased estimator ofA. For a stationary renewal process, ζ _t /t is unbiased for eacht; if theX _i are i.i.d. with densityf(x), then ζ _t /t has this property only iff(x) is of the exponential type and only for this type the numbers of events in consecutive time intervals [0,t], [t, 2t], ... are i.i.d. random variables for arbitraryt > 0.     

Patience and achievement test results

I investigate the relation between high-stakes achievement test scores and students’ patience. I use an experimentally validated measure of time preferences to assess patience in a large sample of Dutch students in secondary school. A one SD increase in the achievement test at the age of 12 predicts 26% of an SD greater level of patience at the age of 15. The results hint at the fact that education can shape preferences.     

Vergleich zweier Operationscharakteristiken

Summary We compare the OC-curvesL _n.c (p) (1) andL _n.c ^* (p) (2). The first is founded on the binomial distribution, the latter relates to the Poisson distribution and is often used as approximation. These OC-curves occur in Statistical Quality Control as probabilities for the acception of a lot as approximations for such probabilities; they are regarded as functions of the fraction defectivep. It is shown that the two OC-curves have exactly one intersection point between 0 and 1, if the acceptance numberc is 1 and the sample sizen is >c+1.Forp between 0 and the intersection pointp _s we have thenL _n.c.(p)>L _n.c ^* (p); from p _s <p1 followsL _n.c(p)n.c ^* (p).An interval is given which coversp _s and with an example it is shown how one might use the results of this paper for the construction of sampling plans.     

Determinants of the demand for imports of Venezuela

In this study we use disaggregated annual data to estimate real income and relative price elasticities of demand for imports of Venezuela. After comparing our estimates with those of previous studies, we conclude that (1) Venezuela has made progress in developing domestic substitutes for imports, and (2) the degree of ‘openness’ in Venezuela increased after 1961. We also find evidence that during the period 1974–1979, the increase in the market value of Venezuela's oil reserves led to an increase in all categories of imports.     

Economic and environmental impacts of the Kyoto Protocol

Abstract In 2003 the Kyoto Protocol, which imposes legally binding greenhouse gas emission constraints on industrialized countries, is likely to enter into force. The Protocol has been celebrated as a milestone in climate protection, but standard economic theory casts doubt that it will go beyond symbolic policy. In this paper, we show that the final concretion of the Kyoto Protocol is consistent with the theoretical prediction: Kyoto more or less boils down to business‐as‐usual without significant compliance costs to ratifying parties. JEL Classification: D58, Q43, Q58
Conséquences économiques et environnementales du protocole de Kyoto En 2003, le protocole de Kyoto, qui impose aux pays industrialisés l'obligation de réduire leurs émissions de gaz à effet de serre, entrera probablement en vigueur. Si le protocole a été accueilli comme un grand pas en avant dans le combat pour protéger l'environnement, la théorie économique jette un regard sceptique sur la portée réelle d'un tel accord et le considére comme un geste symbolique. Dans ce mémoire, on montre que la concrétisation finale de l'accord de Kyoto s'arrime aux prédictions théoriques : Kyoto n'est rien de plus que « business‐as‐usual >> et n'impliquera pas de coûts significatifs pour les parties qui ont signé le protocole.     

Who is who

Praxis / MagazinNews

Who is who     

Technology education for children in primary schools in Finland and Germany: different school systems, similar problems and how to overcome them

Even if the results of international student assessment studies such as PISA or TIMSS show that girls have been catching up in mathematics and natural sciences, there are still remarkable gender differences in the number of males and females studying and working in the technological fields after basic education. Technology is still a male-dominated area. This is true for the German and Finnish societies. Results of the studies conducted in the UPDATE project show that influences on interest in technological themes take place already in early childhood. Therefore, efforts should be put in developing early childhood education and elementary school education, to raise girls’ interests and motivation towards technology. This article reports the results of the UPDATE-WorkPackage3-project mainly in Finland and in Germany. It concentrates on studying elementary school pupils’ (age 6–12), particularly girls’ motivation towards the contents and methods of technology education. Various curriculum documents and national learning conditions are discussed and suggestions for the gender equitable technology education are made.