EN :

While the meaningful theorems of neo-classical theory of the producer are well known, the neo-keynesian counterparts are not. Therefore, this paper will present those new meaningful theorems and their relations with neo-classical theory. On the one hand, this paper is of interest to the theoretician who would want to use the properties of comparative statics of the producer with quantitative rationing. On the other hand, since a neo-keynesian structural form is presented, the econometrician will be interested in imposing the meaningful theorems of this theory as a priori restrictions.

EN :

We derive in the present study a set of equations that yield, through regression analysis, estimates of the elasticity of substitution and of the indexes of technical change attributed to Hicks, Harrod and Solow. On the basis of data drawn from the U.S. non-farm economy, we obtain estimates that are consistent with other findings namely a value for the elasticity of substitution (between labour and capital) that is less than unity and indexes which imply that technology has tended to be Hicks labour-saving, Harrod capital-saving and Solow labour-saving.

EN :

The measurement of the rate of surplus-value, in France, during the last thirty years, refers to the Marxist economic theory of capitalism and araises theoretical and statistical problems.

From a theoretical point of view and after discussing on the legitimacy of measuring the rate of surplus-value, the author mainly evocates the following problems.

1) what kind of workers generate surplus-value?

2) are engineers producers of surplus-value?

3) is it correct to use the data of national accounts to quantify a rate defined on an essential level?

After mentioning the theoretical choices, the author examines the statistical aspects of the problems. According to his results and assumptions, his main conclusion is that the rate of surplus-value, in France, has grown up from 1950. But its rate has been getting slower and slower. The return of capitalist exploitation would have been decreasing. The economic policy worked out from 1974 to 1980 resulted in an increase of the rate of surplus-value without reaching the variations observed during the V^th Républic.

EN :

In this paper, we present a survey of the two main problems of information in insurance markets: moral hazard and adverse selection. Both arise because the insurers are less informed than the insureds. Moral hazard is explained by the fact that the insurer cannot observe, ex ante, the activities of the insured who may have the incentive to change the state of the world in response to insurance coverage. Adverse selection arises since the insurer cannot determine without costs, the risks inherent in the individuals. After defining formally these two problems, we shall present different insurance strategies (private and public) with a view to correct them. In conclusion we shall propose some avenues of research.

EN :

One of the problems in testing the validity of the two-parameter CAPM is the determination of an efficient proxy market portfolio to represent the true market portfolio. We test the mean-variance efficiency of a pre-specified market portfolio by using a method proposed by Roll (1976) for testing the linear relation between the rate of return of an asset and its beta, and hence the mean-variance efficiency of a proxy market portfolio. This procedure exploits the asymptotic exact linearity condition of the rate of return and beta by measuring the rate of decrease of cross-sectional residual variance with respect to increasing time-series sample size. The technique is applied to samples of companies on the Paris Stock Exchange for the period 1969-1978: 144 companies and twenty-nine different time series. The results indicate that although the sum of the squared residuals of a CAPM-type regression declines as the number of time observations increases, the sum of the squared residuals does not approach zero as the temporal sample size increases, as would be required for the market proxy of our pre-specified sample to be efficient.

EN :

This article begins by pointing out, with regard to the study of stock market behaviour, the dangers of distortion inherent in factor analysis in principal components when applied as a method of grouping. As a follow-on to a preceeding contribution dealing with the period 1959-70 this article develops and clarifies the methodological aspects (dangers of factor analysis, utility of percolation method) within the context of the period 1974-79.

The advantage of constituting groups from behaviourally homogenous markets, calculated according to the monthly variations in stock exchange rates of the 13 most important markets, is then analysed. The statistical analysis of links between national stock markets requires prudence as regards the use of notions in which the world stock markets are considered as being a whole, the concept of "economic blocks", indeed the same prudence must be exercised when considering the independence or interdependence of markets and the corresponding generalisations, although the long-term tendency would seem to have been modified since 1974 in a direction favourable to the empirical validation of the concept.