Birth order effects on young students’ academic achievement

We examine birth order effects on academic achievement for ten-year-old students using data for the entire population of fifth graders in Norway 2007/2008. The analysis thus adds to a thin empirical literature focusing on birth order effects among young children. We find that being firstborn confers a significant advantage in families with two, three and four children. The analysis makes two other contributions. First, we provide evidence that unless mother's age at childbirth is included among the control variables, only small and imprecise birth order effects are revealed in families with low socioeconomic status. Second, we provide some evidence that the birth order effects differ across families with highly educated and less educated mothers, which lend support to the resource dilution model over the confluence model.     

On trends and constants in periodic autoregressions

Periodic autoregressions are characterised by autoregressive structures that vary with the season. If a time series is periodically integrated, one needs a seasonally varying differencing filter to remove the stochastic trend. When the periodic regression model contains constants and trends with unrestricted parameters, the data can show diverging seasonal deterministic trends. In this paper we derive explicit expressions for parameter restrictions that result in common deterministic trends under periodic trend stationarity and periodic integration.     

Pitfalls in multi-national long-range planning

The authors of this article argue that too many companies are not getting the benefits which should be produced by their long-range planning systems. Of the many possible explanations for this, the authors concentrate on the major pitfalls which should be avoided in order to ensure good results. The article is based upon the results of a survey of planning pitfalls among corporations in six industrialized countries.     

Dynamic Pricing to Minimize Maximum Regret

We consider a dynamic pricing problem that involves selling a given inventory of a single product over a short, two‐period selling season. There is insufficient time to replenish inventory during this season, hence sales are made entirely from inventory. The demand for the product is a stochastic, nonincreasing function of price. We assume interval uncertainty for demand, that is, knowledge of upper and lower bounds but not a probability distribution, with no correlation between the two periods. We minimize the maximum total regret over the two periods that results from the pricing decisions. We consider a dynamic model where the decision maker chooses the price for each period contingent on the remaining inventory at the beginning of the period, and a static model where the decision maker chooses the prices for both periods at the beginning of the first period. Both models can be solved by a polynomial time algorithm that solves systems of linear inequalities. Our computational study demonstrates that the prices generated by both our models are insensitive to errors in estimating the demand intervals. Our dynamic model outperforms our static model and two classical approaches that do not use demand probability distributions, when evaluated by maximum regret, average relative regret, variability, and risk measures. Further, our dynamic model generates a total expected revenue which closely approximates that of a maximum expected revenue approach which requires demand probability distributions.     

论科学与工程的结构性差异

工程最初被理解为自然科学的应用,然而科学与工程之间的区别是需要进一步澄清的。二者间最简单的区别表现在自然物的科学同人造物的科学之间的区别,而创造性并不能作为科学同工程之间的根本区别。工程师寻找实现目标的手段,手段则是由规则给出的,而且是在技术可能性上有效的。为了更好地理解工程,需要引入技术解释学,并且把工程科学的哲学溶入技术的形而上学之中。     

On the Effect of Risk Aversion in Bimatrix Games

Nash equilibria with identical supports are compared for bimatrix games that are different with respect to the risk aversion of player 2. For equilibria in 2× 2-bimatrix games and for equilibria with efficient supports in coordination games it is established for which cases increased risk aversion of player 2 benefits or hurts player 2.     

The implications of the Lima target: Explorations with a world industrialization model

The Second General Conference of the UNIDO held in Lima in 1975 declared that the share of developing countries in total world industrial production should reach 25% by the year 2000. The model presented in this article has been constructed in order to investigate whether this target is consistent with other more generally accepted goals of development and is feasible within the area of production and trade possibilities.The model is a dynamic, multisectoral, multiregional input-output model. It focuses on the impacts and mutual consistency of targets of growth, regional income distribution, industrialization, consumption levels, and trade. In the empirical application three periods, three regions, and nine sectors have been distinguished to produce intersectorally, interregionally, and intertemporally consistent accounts for the main variables. Since the study is concerned with the maximum possible growth of industrial output of the developing countries, a linear programming approach has been used.The report is organized as follows. After an introduction, the second section describes the mathematical model. The third section contains a detailed explanation of the data basis and of the assumptions made to stimulate the model. The numerical results of the model are discussed in the fourth section, and the main conclusions are given in the fifth.     

Decision problems under uncertainty based on entropy functionals

This essay intends to define the role of entropy, in particular, the role of the maximum entropy criterion with respect to decision analysis and information economics. By considering the average opportunity loss interpretation, the basic hypothesis for Shannon's derivation can be derived from properties of decision problems. Using the representation Bayes Boundary it is possible to show that selecting a single probability from a set by the Maximum Entropy Criterion corresponds to a minimax criterion for decision-making. Since problems of randomly accessing and storing information as well as communicating information can often be stated in terms of coding problems, this result might be used to develop strategies for minimizing retrieval time or communication costs.     

Peer Group Affiliation of Children: The Role of Perceived Popularity,Likeability, and Behavioral Similarity in Bullying

To understand children's peer group affiliation, this study examined to what extent children in naturally occurring groups resemble each other on bullying, likeability, and perceived popularity. Participants were fourth‐ to sixth‐grade pupils (N = 461). Peer groups were identified using the social cognitive map procedure. Resemblance on bullying, likeability, and perceived popularity was evaluated by means of variance components models. Resemblance in peer groups was strongest for perceived popularity, followed by bullying and likeability. Moreover, resemblance on bullying could for a large part be attributed to the high‐perceived popularity of the group, and to a lesser extent, to the low likeability of the group. It is concluded that children showing bullying seem to affiliate with each other most of all to attain or maintain their position in a perceived popular peer group. Results stress the importance of considering the functionality of bullying from a group perspective.