On the unbiasedness of iterated gls estimators

We Formulate sufficienct conditions for the existonce of the expectation of iterated generalized expectation of the iterated generalized least squares estimator, which consequently guarantee its unbiasedness, The analysis is applied to the maximum likelihood estimator in the general linear model with normal disturbances, where a set of assumptions ensures convergence of the iteration as well as unbiasedness.     

Shared contexts and triadic closure in core discussion networks

This paper inquires into structural explanations for triadic closure in networks of confidants with whom one discusses important personal matters. Building upon the assumption that meeting opportunities affect network characteristics, we primarily argue that the social contexts in which network members meet, substantially affect triadic closure. The main empirical findings are (a) that about sixty percent of the triads in core discussion networks are closed triads, which also means that a substantial part of one's strong relations is unconnected, and (b) that meeting network members in the same social contexts is an important condition for, but certainly does not guarantee triadic closure. Importantly, the specific characteristics of social contexts explain why sharing certain contexts positively affects triadic closure, while sharing other contexts does not.     

State and Civil Society in the Political Philosophy of Alexis de Tocqueville

Alexis de Tocqueville discusses extensively the phenomenon of civil society. He distinguishes between the competence of the state on the one hand and the proper competences of free associations on the other. Therefore, the competence of the state should be a limited one. However, since free associations can cause social struggle, the government should also have the ability to limit self-regulation of free associations. Moreover, each government needs a social basis that gives support to this policy of intervention. The central question of this article reads as follows: What method of research is Tocqueville employing to discover this social basis. The conclusion is that his method is to discover what mores form the basis needed by a democratic government to pursue its policy of intervention.     

A comparison of various methods for multivariate regression with highly collinear variables

Regression tends to give very unstable and unreliable regression weights when predictors are highly collinear. Several methods have been proposed to counter this problem. A subset of these do so by finding components that summarize the information in the predictors and the criterion variables. The present paper compares six such methods (two of which are almost completely new) to ordinary regression: Partial least Squares (PLS), Principal Component regression (PCR), Principle covariates regression, reduced rank regression, and two variants of what is called power regression. The comparison is mainly done by means of a series of simulation studies, in which data are constructed in various ways, with different degrees of collinearity and noise, and the methods are compared in terms of their capability of recovering the population regression weights, as well as their prediction quality for the complete population. It turns out that recovery of regression weights in situations with collinearity is often very poor by all methods, unless the regression weights lie in the subspace spanning the first few principal components of the predictor variables. In those cases, typically PLS and PCR give the best recoveries of regression weights. The picture is inconclusive, however, because, especially in the study with more real life like simulated data, PLS and PCR gave the poorest recoveries of regression weights in conditions with relatively low noise and collinearity. It seems that PLS and PCR are particularly indicated in cases with much collinearity, whereas in other cases it is better to use ordinary regression. As far as prediction is concerned: Prediction suffers far less from collinearity than recovery of the regression weights.     

Evaluation of Legal Liability for Technological Risks in View of Requirements for Peaceful Coexistence and Progress

Legal liability for risk‐generating technological activities is evaluated in view of requirements that are necessary for peaceful human coexistence and progress in order to show possibilities for improvement. The requirements imply, given that political decision making about the activities proceeds on the basis of majority rule, that legal liability should be unconditional (absolute, strict) and unlimited (full). We analyze actual liability in international law for various risk‐generating technological activities, to conclude that nowhere is the standard of unconditional and unlimited liability fully met. Apart from that there are enormous differences. Although significant international liability legislation is in place for some risk‐generating technological activities, legislation is virtually absent for others. We discuss fundamental possibilities and limitations of liability and private insurance to secure credible and ethically sound risk assessment and risk management practices. The limitations stem from problems of establishing a causal link between an activity and a harm; compensating irreparable harm; financial warranty; moral hazard in insurance and in organizations; and discounting future damage to present value. As our requirements call for prior agreement among all who are subjected to the risks of an activity about the settlement of these difficult problems, precautionary ex ante regulation of risk‐generating activities may be a more attractive option, either combined with liability stipulations or not. However, if ex ante regulation is not based on the consent of all subjected to the risks, it remains that the basis of liability in the law should be unconditional and unlimited liability.     

Demographic and Personality Characteristics of Internet Child Pornography Downloaders in Comparison to Other Offenders

This research study was conducted to map out the demographic and psychological aspects of Internet child pornography offenders. The backgrounds, characteristics, and MMPI profiles of 22 Internet child pornography offenders were statistically compared to those of 112 perpetrators of other offenses. In comparison to the other sexual offenders, the Internet child pornography offenders turned out to be significantly younger on average, were single and lived alone in most cases, and more often appeared to have no children of their own. It should be noted that the variables of age, being single, living alone, and not having children are associated to one another. Furthermore, no specific MMPI profile was found for Internet child pornography offenders compared to other sexual offenders.     

Pronatalist population policies in some Western European countries

This article is restricted to a comparison of four Western European countries: France, the Federal Republic of Germany, the Netherlands and the United Kingdom. As the crude birthrates and total period fertility rates of these countries indicate, a stabilization of fertility has set in in France, the Netherlands and the United Kingdom. Official government attitudes towards these developments differ greatly, with France having clear pronatalist policy measures, the German Federal Government having only family policy measures, but some member states going further with a policy of family foundation loans. In the Netherlands and the United Kingdom, no official population policy exists, apart from a certain reluctance to accept more foreign immigrants. It must be concluded that the only common characteristic of population policies in the four countries is that they try to enable women to work and care for a family at the same time. The future effect of pronatalist population policy measures is still highly in doubt.This article was originally presented as a paper to the Annual Meeting of the Population Association of America, Washington DC, March 28, 1981.