SUMMARY. This paper describes a principal component analysis of 25 demographic, socio-cultural and economic variables for the period 1966-71. It uses data from 89 countries, including 23 developed ones. The analysis brings out the importance of education and literacy in the process of fertility...

[eng] A wide approach of the irreversibility effect : an application on the conservation of biodiversity. . A decision takes on the characteristics of irreversibility to the extent that it shrinks the space of available options. The irreversibility effect presented by Henry [1974] and further...

[eng] Land prices are generally calculated as the Present Value of their rents. However in the seventies, many statistical models have shown discrepancies when land prices began to decrease. In this paper an autoregressive model has been tested on the French data for the période 1961-1993....

[fre] Les caractéristiques d'une décision séquentielle. Effet irréversibilité et endogénéisation de l'environnement. . L'analyse de la flexibilité est fondée sur les modèles séquentiels en information croissante. La décision initiale d'un modèle séquentiel a des conséquences plus...

The analysis of flexibility is based upon sequential models with growing information. The initial decision of a sequential model has consequences larger than those envisaged in the traditional ?theory of decision??. To enrich it we study consequences of a decision and introduce the distinction...