The use of traditional and modern methods of fertility control in Kinshasa, Zaire

Abstract The practice of post-partum abstinence has been a long-standing tradition in many societies of tropical Africa, yet recent research suggests an erosion of the taboo on post-partum sexual relations as a means of fertility control. The current study among women in the lower income groups in Kinshasa, Zaire, provides evidence of this. There is strong motivation toward child-spacing, as shown by 80 per cent of the women who reported to be currently practising some means of fertility control: 73 per cent with traditional methods, only 7 per cent with modern contraceptives. There appears to be some carry-over of traditional practice, in that abstinence is related to the age and nursing status of the last born child. However, the most widely practised method is withdrawal. This suggests a desire on the part of this population for alternatives to abstinence, an issue with important implications for future family planning programs in Zaire.     

Correlation and variable importance in random forests

This paper is about variable selection with the random forests algorithm in presence of correlated predictors. In high-dimensional regression or classification frameworks, variable selection is a difficult task, that becomes even more challenging in the presence of highly correlated predictors. Firstly we provide a theoretical study of the permutation importance measure for an additive regression model. This allows us to describe how the correlation between predictors impacts the permutation importance. Our results motivate the use of the recursive feature elimination (RFE) algorithm for variable selection in this context. This algorithm recursively eliminates the variables using permutation importance measure as a ranking criterion. Next various simulation experiments illustrate the efficiency of the RFE algorithm for selecting a small number of variables together with a good prediction error. Finally, this selection algorithm is tested on the Landsat Satellite data from the UCI Machine Learning Repository.     

Trends in Mortality Decrease and Economic Growth

The vast literature on extrapolative stochastic mortality models focuses mainly on the extrapolation of past mortality trends and summarizes the trends by one or more latent factors. However, the interpretation of these trends is typically not very clear. On the other hand, explanation methods are trying to link mortality dynamics with observable factors. This serves as an intermediate step between the two methods. We perform a comprehensive analysis on the relationship between the latent trend in mortality dynamics and the trend in economic growth represented by gross domestic product (GDP). Subsequently, the Lee-Carter framework is extended through the introduction of GDP as an additional factor next to the latent factor, which provides a better fit and better interpretable forecasts.     

联合国改革努力的历史发展

联合国改革长期以来是国际社会关注的焦点,为了理解这一进程的未来走向,有必要清醒地认识它所经历的历史发展.联合国改革涉及组织结构、管理程序以及宪制安排三个方面,涵盖国际安全以及经济和社会问题两个主要领域,反映出各国在这些问题上的不同立场和观点.联合国改革努力的不同规划表明,在这些领域取得实质性突破仍然困难重重.     

Market uncertainty and the process of belief formation

Subjective or personal belief formation has been up to now grounded on axioms (e.g., the axioms of Savage) that can be described asintrospection axioms, for they bear only on judgments formed by the individual within himself (e.g., judgments on the ordering of the “acts” in Savage's contribution), excluding every reference to other, possibly external, sources of opinion formation. This current view, linked to the traditional concept ofinstrumental economic rationality, implicitly assumes cognitive capacities that are most of the time out of the reach of any individual. Therefore this view is little or improperly used in the practical world of economics and/or management. An alternative view of belief formation on a market is offered in this article, grounded on a much more modest demand of cognitive capacities from the individual and on a different concept of economic rationality known ascognitive rationality. The model introduces to this end the global concept of market psychology as well as the concept of regular revision of the sets of opinions. Belief formation then appears as a process of deliberation between the individual and the market, rationality emerging within this process as deeply intertwined with the way the individual revises his opinions during the process. The rational treatment of beliefs in view of reaching a decision can consequently be carefully distinguished from their rational formation process.     

Understanding the socio-economic distribution of multiple deprivation: An application of self-organising maps

In this paper we seek to contribute to recent efforts to develop and implement multi-dimensional approaches to social exclusion by applying self-organising maps (SOMs) to a set of material deprivation indicators from the Irish component of EU-SILC. The first stage of our analysis involves the identification of sixteen clusters that confirm the multi-dimensional nature of deprivation in contemporary Ireland and the limitations of focusing solely on income. In going beyond this mapping stage, we consider both patterns of socio-economic differentiation in relation to cluster membership and the extent to which such membership contributes to our understanding of economic stress. Our analysis makes clear the continuing importance of traditional forms of stratification relating to factors such as income, social class and housing tenure in accounting for patterns of multiple deprivation. However, it also confirms the role of acute life events and life cycle and location influences. Most importantly, it demonstrates that conclusions relating to the relative impact of different kinds of socio-economic influences are highly dependent on the form of deprivation being considered. Our analysis suggests that debates relating to the extent to which poverty and social exclusion have become individualized should take particular care to distinguish between different kinds of outcomes. Further analysis demonstrates that the SOM approach is considerably more successful than a comparable latent class analysis in identifying those exposed to subjective economic stress.     

High Stakes and Acceptance Behavior in Ultimatum Bargaining:

This paper presents the results of a within-subject experiment testing whether an increase in the monetary stakes by a factor of 50 – which had never been done before – influences individual behavior in a simple ultimatum bargaining game. Contrary to current wisdom, we found that lowest acceptable offers stated by the responder are proportionally lower in the high-stake condition than in the low-stake condition. This result may be interpreted in terms of the type of utility functions which characterize the subjects. However, in line with prior results, we find that an important increase of the monetary stakes in the ultimatum game has no effect on the offers made by the proposer. Yet, the present research suggests that the reasons underlying these offers are quite different when the stakes are high.     

Ratio-Scale Measurement with Intransitivity or Incompleteness: The Homogeneous Case

In the homogeneous case of one-dimensional objects, we show that any relation that is positive and homothetic can be represented by a ratio-scale and a unique and constant biasing factor. This factor may favor or disfavor the preference for an object over another. In the first case, preferences are complete but not transitive and an object may be preferred even when its value is lower. In the second case, preferences are asymmetric and transitive but not negatively transitive and it may not be sufficient for an object to have a greater value to be preferred. In this manner, the biasing factor reflects the extent to which preferences may depart from a maximization process.