Indifferente en Labiele Evenwichten in Economische Stelsels

In English: Unstable and Indifferent Equilibria in Economic Systems, Revue de l’Institut International de Statistique, Vol. 9, No.1/2, 1941, pp. 36-5

Misunderstandings concerning income distribution policies

In this essay in honour of Professor P. Hennipman the latter's clarity and precision of expression are chosen as an example of how to avoid misunderstanding of his publications. As counterexamples some twenty-odd misunderstandings are set out by the essay's author in the field of income distribution policies, ranging from that specific subject to the theory of economic policy, to economic science and to science as a whole. Several of these misunderstandings are due to the essay's author, while others seem to prevail either among the general public or among scientists

The International Trade Network

Bilateral trade relationships in the international level between pairs of countries in the world give rise to the notion of the International Trade Network (ITN). This network has attracted the attention of network researchers as it serves as an excellent example of the weighted networks, the link weight being defined as a measure of the volume of trade between two countries. In this paper we analyzed the international trade data for 53 years and studied in detail the variations of different network related quantities associated with the ITN. Our observation is that the ITN has also a scale invariant structure like many other real-world networks.Comment: 9 pages, 7 figure

Testing and Applying a Theory of Utility; an attempt to decompose income in compensatory and scarcity rents

Data on income after tax, schooling completed, job held, age, and ‘level of satisfaction’ of 2663 members of the Dutch Consumer Union have been used to estimate regression equations of two types. Type I may be called a specification of a utility function, Type II an ‘earnings function’ (where income after tax was used as earnings). For both types a number of alternatives were estimated both with regard to mathematical shape and with regard to variables included. Defining equitable or justified income differences as differences which do not change the level of satisfaction, a formula for equitable incomes for given combinations of job, schooling and age can be derived from Type I equations. All regression coefficients are found to be lower than the corresponding earnings function coefficients. The latter can then be decomposed into a ‘compensatory’ component and a ‘scarcity rent’ component

Income distribution: Second thoughts

As a follow-up of his book on income distribution the author reformulates his version on the scarcity theory of income from productive contributions. The need to introduce into an earnings theory several job characteristics, non-cognitive as well as cognitive, and the corresponding personality traits is stressed, the latter subdivided into innate and learnable capabilities. The theory is presented in two alternative mathematical versions: one where job and person characteristics are continuous and one where they have discrete values and their frequencies assume continuous values. Although, mainly in the United States, numerous empirical inquiries have been made, job characteristics and the corresponding personal characteristics have not been included in sufficient number. I want to express my profound gratitude to Professor Robert H. Haveman, who not only published a deep-delving review article on my book Income Distribution: Analysis and Policies but also commented on an earlier text of the present article. I also owe a great debt to Professor Jan Pen who in a long series of discussions challenged a number of my concepts and figures. Finally I want to thank Dr. S. K. Kuipers for helpful comments on an earlier draft

From Oxford to Bristol and Back: The Invention of Scientific Wildlife Television

In the 1960s, two scientists from Oxford University, Niko Tinbergen and Gerald Thompson, began using film as part of their scientific practice. The BBC’s Natural History Unit (NHU) in Bristol quickly got wind of their work and started collaborating with them to develop a new approach to wildlife television making. Tinbergen, the founder of ethology, brought intellectual foundations to it, creating, with Christopher Parsons, stories of wildlife informed by the theory of evolution. Thompson provided a technological edge which enabled the Bristol NHU producers to bring a new perspective to the subject matter they were showing in their programmes. The two collaborations also led them to further define their identity as experts in wildlife television making

Searching for Planets in the Hyades II: Some Implications of Stellar Magnetic Activity

The Hyades constitute a homogeneous sample of stars ideal for investigating the dependence of planet formation on the mass of the central star. Due to their youth, Hyades members are much more chromospherically active than stars traditionally surveyed for planets using high precision radial velocity (RV) techniques. Therefore, we have conducted a detailed investigation of whether magnetic activity of our Hyades target stars will interfere with our ability to make precise RV searches for substellar companions. We measure chromospheric activity (which we take as a proxy for magnetic activity) by computing the equivalent of the R'HK activity index from the Ca II K line. is not constant in the Hyades: we confirm that it decreases with increasing temperature in the F stars, and also find it decreases for stars cooler than mid-K. We examine correlations between simultaneously measured R'HK and RV using both a classical statistical test and a Bayesian odds ratio test. We find that there is a significant correlation between R'HK and the RV in only 5 of the 82 stars in this sample. Thus, simple Rprime HK-RV correlations will generally not be effective in correcting the measured RV values for the effects of magnetic activity in the Hyades. We argue that this implies long timescale activity variations (of order a few years; i.e., magnetic cycles or growth and decay of plage regions) will not significantly hinder our search for planets in the Hyades if the stars are closely monitored for chromospheric activity. The trends in the RV scatter (sigma'_v) with , vsini, and P_rot for our stars is generally consistent with those found in field stars in the Lick planet search data, with the notable exception of a shallower dependence of sigma'_v on for F stars.Comment: 15 pages, 7 figures, 3 tables; To appear in the July 2002 issue of The Astronomical Journa

Beyond persons: extending the personal / subpersonal distinction to non-rational animals and artificial agents

The distinction between personal level explanations and subpersonal ones has been subject to much debate in philosophy. We understand it as one between explanations that focus on an agent’s interaction with its environment, and explanations that focus on the physical or computational enabling conditions of such an interaction. The distinction, understood this way, is necessary for a complete account of any agent, rational or not, biological or artificial. In particular, we review some recent research in Artificial Life that pretends to do completely without the distinction, while using agent-centered concepts all the way. It is argued that the rejection of agent level explanations in favour of mechanistic ones is due to an unmotivated need to choose among representationalism and eliminativism. The dilemma is a false one if the possibility of a radical form of externalism is considered

The International Trade Network: weighted network analysis and modelling

Tools of the theory of critical phenomena, namely the scaling analysis and universality, are argued to be applicable to large complex web-like network structures. Using a detailed analysis of the real data of the International Trade Network we argue that the scaled link weight distribution has an approximate log-normal distribution which remains robust over a period of 53 years. Another universal feature is observed in the power-law growth of the trade strength with gross domestic product, the exponent being similar for all countries. Using the 'rich-club' coefficient measure of the weighted networks it has been shown that the size of the rich-club controlling half of the world's trade is actually shrinking. While the gravity law is known to describe well the social interactions in the static networks of population migration, international trade, etc, here for the first time we studied a non-conservative dynamical model based on the gravity law which excellently reproduced many empirical features of the ITN.Comment: 5 pages, 5 figure